Lorna Mitchell has posted a quick guide to compiling PECL extensions to her site today. This is for those users on unix-based systems that might need to manually compile with some custom options (or may be working on your own extension and may just need to test it).
There are lots of reasons why you might like to compile your own PHP extensions. [...] I haven't seen a really approachable guide anywhere, we tend to speak of extensions in hushed tones, and actually it isn't particularly tricky so here is my quick how-to guide.
The process is relatively simple for those familiar with the command line and the steps involved in compiling software. There's some special PHP-only steps you'll have to take before compiling the code to make sure it's ready to be a PHP extension. Then it's up to the usual configure+make_make install to ensure the .so file is correctly generated.