Tested on two systems running OS X 10.1.5 with both CVS 
snapshot and PHP 4.2.1.  Both systems have libxml 1.8.17 as 
well as libxml2 2.4.22.

In my configure script, it works fine if I just comment out 
the line "--with-dom=/sw", otherwise I get this:

/bin/sh libtool --silent --mode=link gcc -export-dynamic -
DPHP_ATOM_INC -I/Users/halim/apache/php4-200206250900/
include -I/Users/halim/apache/php4-200206250900/main -I/
Users/halim/apache/php4-200206250900 -I/Users/halim/apache/
php4-200206250900/Zend -I/sw/include -I/sw/include/libxml2 
-I/sw/include/freetype2 -I/sw/include/pspell  -traditional-
cpp -no-cpp-precomp -I/Users/halim/apache/php4-
200206250900/TSRM -g -O2  -L/sw/lib -bind_at_load -R /sw/
lib ext/zlib/zlib.lo ext/zlib/zlib_fopen_wrapper.lo ext/
bcmath/bcmath.lo ext/bcmath/number.lo ext/bcmath/libbcmath/
src/add.lo ext/bcmath/libbcmath/src/div.lo ext/bcmath/
libbcmath/src/init.lo ext/bcmath/libbcmath/src/neg.lo ext/
bcmath/libbcmath/src/outofmem.lo ext/bcmath/libbcmath/src/
raisemod.lo ext/bcmath/libbcmath/src/rt.lo ext/bcmath/
libbcmath/src/sub.lo ext/bcmath/libbcmath/src/compare.lo 
ext/bcmath/libbcmath/src/divmod.lo ext/bcmath/libbcmath/
src/int2num.lo ext/bcmath/libbcmath/src/num2long.lo ext/
bcmath/libbcmath/src/output.lo ext/bcmath/libbcmath/src/
recmul.lo ext/bcmath/libbcmath/src/sqrt.lo ext/bcmath/
libbcmath/src/zero.lo ext/bcmath/libbcmath/src/debug.lo 
ext/bcmath/libbcmath/src/doaddsub.lo ext/bcmath/libbcmath/
src/nearzero.lo ext/bcmath/libbcmath/src/num2str.lo ext/
bcmath/libbcmath/src/raise.lo ext/bcmath/libbcmath/src/
rmzero.lo ext/bcmath/libbcmath/src/str2num.lo ext/bz2/
bz2.lo ext/ctype/ctype.lo ext/curl/curl.lo ext/dba/dba.lo 
ext/dba/dba_cdb.lo ext/dba/dba_db2.lo ext/dba/dba_dbm.lo 
ext/dba/dba_gdbm.lo ext/dba/dba_ndbm.lo ext/dba/dba_db3.lo 
ext/domxml/php_domxml.lo ext/exif/exif.lo ext/ftp/
php_ftp.lo ext/ftp/ftp.lo ext/gd/gd.lo ext/gd/gdcache.lo 
ext/gd/gdttf.lo ext/gd/gdt1.lo ext/gettext/gettext.lo ext/
gmp/gmp.lo ext/mbstring/mbfilter_ja.lo ext/mbstring/
mbfilter_cn.lo ext/mbstring/mbfilter_tw.lo ext/mbstring/
mbfilter_kr.lo ext/mbstring/mbfilter_ru.lo ext/mbstring/
mbfilter.lo ext/mbstring/mbstring.lo ext/mbstring/
mbregex.lo ext/mbstring/php_mbregex.lo ext/mysql/
php_mysql.lo ext/mysql/libmysql/libmysql.lo ext/mysql/
libmysql/errmsg.lo ext/mysql/libmysql/net.lo ext/mysql/
libmysql/violite.lo ext/mysql/libmysql/password.lo ext/
mysql/libmysql/my_init.lo ext/mysql/libmysql/my_lib.lo ext/
mysql/libmysql/my_static.lo ext/mysql/libmysql/my_malloc.lo 
ext/mysql/libmysql/my_realloc.lo ext/mysql/libmysql/
my_create.lo ext/mysql/libmysql/my_delete.lo ext/mysql/
libmysql/my_tempnam.lo ext/mysql/libmysql/my_open.lo ext/
mysql/libmysql/mf_casecnv.lo ext/mysql/libmysql/my_read.lo 
ext/mysql/libmysql/my_write.lo ext/mysql/libmysql/errors.lo 
ext/mysql/libmysql/my_error.lo ext/mysql/libmysql/
my_getwd.lo ext/mysql/libmysql/my_div.lo ext/mysql/
libmysql/mf_pack.lo ext/mysql/libmysql/my_messnc.lo ext/
mysql/libmysql/mf_dirname.lo ext/mysql/libmysql/
mf_fn_ext.lo ext/mysql/libmysql/mf_wcomp.lo ext/mysql/
libmysql/typelib.lo ext/mysql/libmysql/safemalloc.lo ext/
mysql/libmysql/my_alloc.lo ext/mysql/libmysql/mf_format.lo 
ext/mysql/libmysql/mf_path.lo ext/mysql/libmysql/
mf_unixpath.lo ext/mysql/libmysql/my_fopen.lo ext/mysql/
libmysql/mf_loadpath.lo ext/mysql/libmysql/my_pthread.lo 
ext/mysql/libmysql/my_thr_init.lo ext/mysql/libmysql/
thr_mutex.lo ext/mysql/libmysql/mulalloc.lo ext/mysql/
libmysql/string.lo ext/mysql/libmysql/default.lo ext/mysql/
libmysql/my_compress.lo ext/mysql/libmysql/array.lo ext/
mysql/libmysql/my_once.lo ext/mysql/libmysql/list.lo ext/
mysql/libmysql/my_net.lo ext/mysql/libmysql/dbug.lo ext/
mysql/libmysql/strmov.lo ext/mysql/libmysql/strxmov.lo ext/
mysql/libmysql/strnmov.lo ext/mysql/libmysql/strmake.lo 
ext/mysql/libmysql/strend.lo ext/mysql/libmysql/strfill.lo 
ext/mysql/libmysql/is_prefix.lo ext/mysql/libmysql/
int2str.lo ext/mysql/libmysql/str2int.lo ext/mysql/
libmysql/strinstr.lo ext/mysql/libmysql/strcont.lo ext/
mysql/libmysql/strcend.lo ext/mysql/libmysql/bchange.lo 
ext/mysql/libmysql/bmove.lo ext/mysql/libmysql/bmove_upp.lo 
ext/mysql/libmysql/longlong2str.lo ext/mysql/libmysql/
strtoull.lo ext/mysql/libmysql/strtoll.lo ext/mysql/
libmysql/charset.lo ext/mysql/libmysql/ctype.lo ext/
ncurses/ncurses.lo ext/ncurses/ncurses_fe.lo ext/ncurses/
ncurses_functions.lo ext/openssl/openssl.lo ext/overload/
overload.lo ext/pcre/pcrelib/maketables.lo ext/pcre/
pcrelib/get.lo ext/pcre/pcrelib/study.lo ext/pcre/pcrelib/
pcre.lo ext/pcre/php_pcre.lo ext/posix/posix.lo ext/pspell/
pspell.lo ext/session/session.lo ext/session/mod_files.lo 
ext/session/mod_mm.lo ext/session/mod_user.lo ext/standard/
array.lo ext/standard/base64.lo ext/standard/
basic_functions.lo ext/standard/browscap.lo ext/standard/
crc32.lo ext/standard/crypt.lo ext/standard/cyr_convert.lo 
ext/standard/datetime.lo ext/standard/dir.lo ext/standard/
dl.lo ext/standard/dns.lo ext/standard/exec.lo ext/
standard/file.lo ext/standard/filestat.lo ext/standard/
flock_compat.lo ext/standard/formatted_print.lo ext/
standard/fsock.lo ext/standard/head.lo ext/standard/html.lo 
ext/standard/image.lo ext/standard/info.lo ext/standard/
iptc.lo ext/standard/lcg.lo ext/standard/link.lo ext/
standard/mail.lo ext/standard/math.lo ext/standard/md5.lo 
ext/standard/metaphone.lo ext/standard/microtime.lo ext/
standard/pack.lo ext/standard/pageinfo.lo ext/standard/
parsedate.lo ext/standard/quot_print.lo ext/standard/
rand.lo ext/standard/reg.lo ext/standard/soundex.lo ext/
standard/string.lo ext/standard/scanf.lo ext/standard/
syslog.lo ext/standard/type.lo ext/standard/uniqid.lo ext/
standard/url.lo ext/standard/url_scanner.lo ext/standard/
var.lo ext/standard/versioning.lo ext/standard/assert.lo 
ext/standard/strnatcmp.lo ext/standard/levenshtein.lo ext/
standard/incomplete_class.lo ext/standard/url_scanner_ex.lo 
ext/standard/ftp_fopen_wrapper.lo ext/standard/
http_fopen_wrapper.lo ext/standard/php_fopen_wrapper.lo 
ext/standard/credits.lo ext/standard/var_unserializer.lo 
ext/standard/ftok.lo ext/standard/aggregation.lo ext/
tokenizer/tokenizer.lo ext/xml/xml.lo regex/regcomp.lo 
regex/regexec.lo regex/regerror.lo regex/regfree.lo TSRM/
TSRM.lo TSRM/tsrm_strtok_r.lo TSRM/tsrm_virtual_cwd.lo 
main/main.lo main/snprintf.lo main/spprintf.lo main/
php_sprintf.lo main/safe_mode.lo main/fopen_wrappers.lo 
main/alloca.lo main/php_ini.lo main/SAPI.lo main/rfc1867.lo 
main/php_content_types.lo main/strlcpy.lo main/strlcat.lo 
main/mergesort.lo main/reentrancy.lo main/php_variables.lo 
main/php_ticks.lo main/streams.lo main/network.lo main/
php_open_temporary_file.lo main/php_logos.lo main/output.lo 
main/memory_streams.lo main/user_streams.lo Zend/
zend_language_parser.lo Zend/zend_language_scanner.lo Zend/
zend_ini_parser.lo Zend/zend_ini_scanner.lo Zend/
zend_alloc.lo Zend/zend_compile.lo Zend/zend_constants.lo 
Zend/zend_dynamic_array.lo Zend/zend_execute_API.lo Zend/
zend_highlight.lo Zend/zend_llist.lo Zend/zend_opcode.lo 
Zend/zend_operators.lo Zend/zend_ptr_stack.lo Zend/
zend_stack.lo Zend/zend_variables.lo Zend/zend.lo Zend/
zend_API.lo Zend/zend_extensions.lo Zend/zend_hash.lo Zend/
zend_list.lo Zend/zend_indent.lo Zend/
zend_builtin_functions.lo Zend/zend_sprintf.lo Zend/
zend_ini.lo Zend/zend_qsort.lo Zend/zend_multibyte.lo Zend/
zend_execute.lo sapi/cgi/cgi_main.lo sapi/cgi/getopt.lo 
main/internal_functions.lo -lexpat -lpspell -lncurses -lgmp 
-lintl -lgd -lfreetype -lpng -lz -ljpeg -lz -lm -liconv -lz 
-lxml2 -ldb -lgdbm -lcurl -ldl -lcurl -lbz2 -lz -lssl -
lcrypto -lm -ldl -ldl -o php
(snipped a bunch of warnings from other unrelated stuff)
/usr/bin/ld: Undefined symbols:
__._7filebuf
___11fstreambaseiPCcii
___vt_11fstreambase.3ios
___vt_3ios
___vt_7istream.3ios
___vt_8ifstream.3ios
___iomanip_setw__FR3iosi
___ls__7ostreamPCc
___ls__H1Zi_R7ostreamRCt6smanip1ZX01_RB0
__IO_getc
__IO_init_global_stdio
_flush__7ostream
(snipped a bunch of warnings from other unrelated stuff)
make: *** [php] Error 1