2 Standalone G2s, want to conver one to Multisite

This is about converting a standalone Gallery into a multisite copy. Here's my scenario.

I have a G2 installation @ http://watsonalgas.com.ru/gallery2, and another @ http://mali.net.ru/gallery2 (this one is actually a subdomain, so it would be http://watsonalgas.com.ru/mali/gallery2 or http://mali.watsonalgas.com.ru/gallery2). I want to convert the second installation into a multisite of the first, since they are on the same server and it will supposedly save me some space, but I want to keep the same databases,and all the same info, but the second one in still in beta, so it will need to be upgraded in the process.

This is all I found about it, and it's pretty good:

http://gallery.menalto.com/node/35733?highlight=multisite

I was wondering if what is in that post applied to me, and if yes, which steps I should follow. It seems the person there didn't have two existing installations, but just one and wanted to move it, which is not the same as what I want to do.
Any help would be great, thanks.