adding functions to php4...

Hi, I am trying to add some statistical functions to php4. Currently I am using php4.0.1pl2 as apache module(1.3.12) on solaris 2.7. I compiled C-source files into library say, libstat.a and installed it under /usr/local/lib. I made ext/stat directory and necessary files by looking at the other directories. Now I do not know what else do I have to modify. What I am hoping for is to specify on my configure line as --with-stat and do make. I did a similar job in php3 but in php4 lots of structures are changed. Could someone shed some lights on this ? I have read apidoc.txt, of course. Thanks in advance Jinsoo