Is it possible to add new multis into uo, such as houses that can be placed? I'd like to make a few new houses as well as keep the old one, but have no idea where to start.

Can someone do me and maybe some others with the same ideas a HUGE favour and post step by step how to add in a multi? If any 3rd party tools are needed then post a link where to dload etc.

I've been using POL for a couple of years now but have never done this type of thing. Thanks.