Installing wpg2 when wp is on a different database

I’ve got the latest Gallery2 version (2.2.1) and WordPress 2.2. They are on different databases and the FAQ for wpg2 says installation on different databases is possible. I’ve scoured the forums and can’t find a single instance of someone who did this. Am I hallucinating or is this a lost cause? Please respond to this post with a detailed explanation on how to do this or please point me a site/post on how to do this. Thanks in advance!