Apache needs to be installed as DSO rather then static.
If its installed as DSO it can have other software modules installed separately and loaded at the time of Apache starting.
If its installed as static you have to compile PHP at the time of compiling Apache.
You will need to recompile Apache as DSO and PHP at the same time.
Its not as bad as it sounds, I normally install to another directory say /usr/local/newapache if the install seems to work fine I copy the config files (httpd.conf etc..) across to the new conf directory (/usr/local/apache/conf) stop the running Apache and try and start the new install.
If it all works, I tar up the old Apache directory (just in case) and remove it. Then create a symbolic link from /usr/local/apache to /usr/local/newapache.
Good Luck
D.