I've compiled pdflib 3.0.4 as follows;
./configure --without-py --without-tcl --without-perl
make
make install

..and then php4.3.2rc1;
./configure \
--with-apache=../apache_1.3.27 \
--with-config-file-path=/etc \
--enable-inline-optimization \
--enable-mime-magic \
--enable-magic-quotes \
--enable-track-vars \
--with-xml \
--with-dom \
--with-xmlrpc \
--with-mysql=/usr/local/mysql \
--enable-sockets \
--with-ldap \
--with-imap=/usr/local/imap-2002b \
--with-imap-ssl=/usr/local \
--with-mm \
--enable-memory-limit \
--enable-bcmath \
--enable-sigchild \
--with-zlib=/usr \
--with-curl=/usr/local \
--with-dom=/usr/include/libxml2/libxml \
--enable-exif \
--enable-ftp \
--with-gettext=/usr/share \
--with-gd \
--with-ttf \
--with-freetype-dir=/usr/local/include/freetype2/freetype \
--enable-gd-imgstrttf \
--with-png-dir=/usr \
--with-jpeg-dir=/usr \
--with-tiff-lib=/usr \
--with-mcal=../libmcal \
--with-openssl=/usr/local/ssl \
--with-mcrypt \
--with-mhash \
--with-pspell \
--with-imagick \
--with-pdflib=/usr/local

make
make install

"make install" returns the following:
Installing PHP CLI binary:        /usr/local/bin/
Installing PHP CLI man page:      /usr/local/man/man1/
Installing PHP SAPI module
Installing shared extensions:     /usr/local/lib/php/extensions/no-debug-non-zts-20020429/
Installing PEAR environment:      /usr/local/lib/php/
HTTP/1.0 0 X
Content-type: text/html

PHP Fatal error:  PDFlib error: Version mismatch in wrapper code in Unknown on line 0
[PEAR] Archive_Tar    - already installed: 0.9
[PEAR] Console_Getopt - already installed: 1.0
[PEAR] PEAR           - already installed: 1.0.1
HTTP/1.0 0 X
Content-type: text/html

PHP Fatal error:  PDFlib error: Version mismatch in wrapper code in Unknown on line 0
[PEAR] DB             - already installed: 1.3
[PEAR] HTTP           - already installed: 1.2
[PEAR] Mail           - already installed: 1.0.1
[PEAR] Net_SMTP       - already installed: 1.0
[PEAR] Net_Socket     - already installed: 1.0.1
[PEAR] XML_Parser     - already installed: 1.0.1
[PEAR] XML_RPC        - already installed: 1.0.4
Installing build environment:     /usr/local/lib/php/build/
Installing header files:          /usr/local/include/php/
Installing helper programs:       /usr/local/bin/
  program: phpize
  program: php-config
  program: phpextdist


I have tried using both the existing php-4.3.2RC1/ext/pdf/ files and copying the files from pdflib-4.0.3/bind/php/ext/pdf/* to php-4.3.2RC1/ext/pdf/ with the same result.