Based on Dao Hoang Son's tutorial (itself based on Dan Spencer's Lion tutorial), as well as a few corrections of my own, I came up with the following script. It fetches and installs University of Washington's IMAP library, then the PCRE – Perl Compatible Regular Expressions library, and finally the PHP IMAP extension itself.
Please study the script yourself before running it, or run it line by line. It performs no error checking, meaning it might totally wreck your machine — and I'm not responsible if it does. Keep a Time Machine backup around and unplugged from the computer, in case it does.
The script wasn't yet tested in its complete form; it's an approximate transcript of commands I ran in shell. But since I'll keep it around in case I ever need to re-run it, I'm fairly certain it works.
UPDATE December 24th 2012 – Merry Christmas! I've applied corrections based on Mehmet's comment. He also comments you need to install autoconf before running the script (so phpize can work). I already had it installed.
Filesizes for stuff I downloaded: 1.990.304 – imap-2007f.tar.gz, 1.539.766 – pcre-8.20.tar.gz, 12.926.535 – PHP-5.3.15.tar.gz
#!/bin/bash BUILDDIR=/tmp/phpimapmountainlion mkdir "$BUILDDIR" echo " " echo "= FETCHING AND INSTALLING IMAP" echo " " cd "$BUILDDIR" wget -c ftp://ftp.cac.washington.edu/imap/imap-2007f.tar.gz rm -rf imap-2007f tar xvvfz imap-2007f.tar.gz cd imap-2007f make osx EXTRACFLAGS="-arch i386 -arch x86_64 -g -Os -pipe -no-cpp-precomp" sudo mkdir -p /usr/local/imap-2007f/include sudo cp c-client/*.h /usr/local/imap-2007f/include sudo mkdir -p /usr/local/imap-2007f/lib sudo cp c-client/c-client.a /usr/local/imap-2007f/lib/libc-client.a echo " " echo "= FETCHING AND INSTALLING PCRE" echo " " cd "$BUILDDIR" wget "http://sourceforge.net/projects/pcre/files/pcre/8.20/pcre-8.20.tar.gz" rm -rf pcre-8.20 tar xvvfz pcre-8.20.tar.gz cd pcre-8.20 ./configure --prefix=/usr/local make sudo make install echo " " echo "= FETCHING AND INSTALLING PHP-IMAP" echo " " cd "$BUILDDIR" PHPVERSION=`php --version|head -n1|cut -f 2 -d ' '` ##git clone -b "PHP-$PHPVERSION" https://github.com/php/php-src.git php-src wget --no-check-certificate -c https://github.com/php/php-src/tarball/PHP-5.3.15 -O PHP-5.3.15.tar.gz tar xvvfz PHP-5.3.15.tar.gz cd `ls |grep php-php-src-|head -n1` cd ext/imap phpize ./configure --with-imap=/usr/local/imap-2007f --with-kerberos --with-imap-ssl make sudo cp modules/imap.so /usr/lib/php/extensions/no-debug-non-zts-20090626/