I managed to get the custom INI to load, but its still loading other .ini files from the default location.
I created an fcgi wrapper that passed the ini value as a parameter. That worked. Now just these other ini's need to be loaded from the same dir as my custom ini.
The problem is the other .ini files are overriding the settings in my custom php.ini =/
I realize the problem now is that the php.fcgi was compiled with a custom path parameter. So that's a problem. I might have to recompile it using a different location or none at all. I'd hate to have to compile an fcgi for each domain =/