Custom php.ini with mult subdomains

I’ve been trying to think of a better way of doing this, and can’t seem to find on the support wiki exactly what im trying to do.

Basically I have a folder structure as follows:
----webapp [subdomain here]
----webapp [subdomain here]
—[shared library - amfphp / pear / adodb etc.]

basically i needed to get access to php.ini but not having to create a new cgi-bin / php.ini file for every client. ive had no problems with setting it up for each client individually, but what is the other options for sharing a custom php.ini file accross multiple subdomains?
i havn’t tried it yet, but would symlinks work? or is that a security issue?

thanks in advance,

thanks, just what i was looking for.