This used to be a doc I wrote/used to compile Apache on our production webservers at work.
I currently use ApacheToolbox, which I have made some patches to. The main patch is to disable LDAP in the bin/php-ldap. For those of you that have a need for ldap support in php on your Solaris servers, feel free to find a way around this (set it up to find the openldap libs).
For frontpage support, I used mod_frontpage-1.6.1. Hat's off to Martin Blapp of FreeBSD fame for maintaining this package.
I haven't finished debugging this fully yet, but I've noticed compile problems when compiling apache with a prefix of /usr on solaris. This stems in part from using gcc on solaris with libc installed in /usr/local from what I can tell. It had problems finding some array handling functions from libc. All the problems were resolved when I switched the install prefix for openssl and apache back to /usr/local. I was able to hack around this, but noticed it broke some things (suExec, and subsequently FPE). Again, the permanent/clean fix was to compile apache (and openssl) with a prefix of /usr/local.