Can this be done? Basically what I need is to have 3-4 domains with XOOPS running. The trick is that I need them to have the same database for users.

For example a new user that registers on xoops-site-one.com would show up in the New Members block of xoops-site-two.com and xoops-site-three.com, as well as users registering on one site could log-in on the other sites with the same login info.

I've read the topic on How can i share tables between sites with MySQL? but basically what I need is to have one databse that could be access by various domains...

Any suggestion? Ideas?

The method you link to above is certainly the easiest solution.