First of all, installing the Extended Preferences plugin is just a matter of moving a single dll into your .gaim/plugins folder, so I'm not having a problem installing it. In fact, in the previous version of PortableGaim (1.5beta1), it did work. After upgrading to 1.5beta2 (copying the entire .gaim directory elsewhere, extracting the new version over the old, copying the .gaim directory back), it stopped working, even though the dll is still in the right place. What happened?
it's a slightly different config. Any config changes made to Gaim by the plugin on install?
Sometimes, the impossible can become possible, if you're awesome!
I re-copied the dll from the zip file, but the plugin still doesn't appear in the plugins list in the preferences.