I've just recently begun dabbling in using extras for adium, however i can't seem to get them installed using the adiumxtras webiste. when i click the button to install it says "unsupported protocall" and when i try to download the files directly, i don't know how to get adium to recognize them.
Once you've downloaded them, unzip the file. The double-click on the unzipped file and it should automatically add to adium. You'll get a message like "extra has been added. would you like to open the adium preferences?" or some such once it's done.
Presumably he's talking about using webinstall, rather than downloading and installing. I'm not sure why Adium wouldn't be registering as the adiumxtra:// handler... maybe try the beta?