Using FreeTDS 0.50 and php4.0.4pl1 with /configure  --with-config-file-path=/bin/lsd --disable-debug --enable-safe-mode --enable-track-vars --enable-magic-quotes --enable-force-cgi-redirect --with-mysql=/usr/local/mysql --enable-memory-limit --with-sybase=/usr/local/freetds --enable-inline-optimization --with-ftp results in:

make[1]: Entering directory `/root/pacotes/php-4.0.4pl1'
/bin/sh /root/pacotes/php-4.0.4pl1/libtool --silent --mode=link gcc  -I. -I/root
/pacotes/php-4.0.4pl1/ -I/root/pacotes/php-4.0.4pl1/main -I/root/pacotes/php-4.0
.4pl1 -I/root/pacotes/php-4.0.4pl1/Zend -I/usr/local/mysql/include/mysql -I/usr/
local/freetds/include -I/root/pacotes/php-4.0.4pl1/ext/xml/expat/xmltok -I/root/
pacotes/php-4.0.4pl1/ext/xml/expat/xmlparse -I/root/pacotes/php-4.0.4pl1/TSRM  -
DXML_BYTE_ORDER=12 -g -O2   -o php -export-dynamic       stub.lo libphp4.la
.libs/libphp4.a(php_sybase_db.o): In function `php_sybase_do_connect':
/root/pacotes/php-4.0.4pl1/ext/sybase/php_sybase_db.c:354: undefined reference t
o `DBSETLCHARSET'
collect2: ld returned 1 exit status
make[1]: *** [php] Error 1
make[1]: Leaving directory `/root/pacotes/php-4.0.4pl1'
make: *** [all-recursive] Error 1         

Please notice that php-4.0.0 does compile VERY well with the same configure and libs and et all.