Untar them, and run the configure program on Apache like so.
./configure --exec-prefix=/usr \
--localstatedir=/var \
--mandir=/usr/share/man \
--libexecdir=/System/Library/Apache/Modules \
--iconsdir=/System/Library/Apache/Icons \
--includedir=/System/Library/Frameworks/Apache.framework/Versions/1.3/Headers \
--enable-shared=max \
--enable-module=most \
--target=apache
If you want the compiler to do some optimization, you may also want to add this line:
setenv OPTIM=-O2
Next, go to the PHP 4 source directory and configure it.
./configure --prefix=/usr \
--sysconfdir=/etc \
--localstatedir=/var \
--mandir=/usr/share/man \
--with-xml \
--with-apache=/src/apache_1.3.12
Now, reconfigure Apache to build in PHP 4.
./configure --exec-prefix=/usr \
--localstatedir=/var \
--mandir=/usr/share/man \
--libexecdir=/System/Library/Apache/Modules \
--iconsdir=/System/Library/Apache/Icons \
--includedir=/System/Library/Frameworks/Apache.framework/Versions/1.3/Headers \
--enable-shared=max \
--enable-module=most \
--target=apache \
--activate-module=src/modules/php4/libphp4.a
cp php.ini-dist /usr/local/bin/php.ini
or (if your don't have a local directory)
cp php.ini-dist /usr/bin/php.ini
.