php install problem couldnt find libphp4.so

I am a beginner in Slackware and by default I had apache , php 4.3.3 and MySQL 4.0.15a installed. I removed apache cause I wanted to install newer version (2.0.49) I installed it with default options in usr/local/apache2.
These are the modules installed.
Compiled in modules:
* core.c
* mod_access.c
* mod_auth.c
* mod_include.c
* mod_log_config.c
* mod_env.c
* mod_setenvif.c
* prefork.c
* http_core.c
* mod_mime.c
* mod_status.c
* mod_autoindex.c
* mod_asis.c
* mod_cgi.c
* mod_negotiation.c
* mod_dir.c
* mod_imap.c
* mod_actions.c
* mod_userdir.c
* mod_alias.c
* mod_so.c
Now that the apache is up and running I want to add php support. I added a few lines in httpd.conf:
LoadModule php4_module /usr/libexec/libphp4.so
AddType application/x-httpd-php .php
I copied my php.ini (was there by default) to /usr/local/apache2/lib (not sure why exactly there-read in a doc page)
After all this the following error occurs when I start the apache.
Cannot load /usr/libexec/libphp4.so into server: libmm.so.13: cannot open shared object file: No such file or directory
I suppose I need to add one more module mod_php4.c (again read it in a doc somewhere) but in the apache's documentation there is no such module and anyway I donno how to add a module.
http://httpd.apache.org/docs-2.0/mod/
So I donno what the problem is? What is more I want to run MySQL as well (also installed by default with the OS).
Someone, please help me fix this problem and tell me how to check if everything is running smoothly.
Thanks in advance.

P.S. Yes, libphp4.so is in /usr/libexec/ and rights 755 owned by root.