Enviroment Variables Inside PHP.INI

Hi. I'm building a portable webserver, wich will include php5. The problem i am having is that i cannot make the extensions to work. What i need is to specify an enviroment variable for extensions_dir directive. I've alread tested $VAR, %VAR%, ${VAR} with no luck. I've already tested ussing httpd.conf file config, wich set the LOCAL config for this directive, but php allways looks for the Main ref to locate the extension thats intented to be loaded. If i try to use the usual way, like "./ext" and so, dont work either, because the php binaries default ext folder is in another place under /usr/local/php5. So the question is, is there a way to use enviroment variables to specify a folder or something? like apache does with ${VAR} ? Thanks. Roberto.