This is the closest tutorial that I have found for what you want.
www.servuo.com
How to create deed-placeable custom houses
Tools you will need... Pandora's Box UO Architect UO Fiddler Mulpatcher or I think there is a MUL exporter plug-in for UO Fiddler but I have not tried that. Create a building using manual placement of static objects in GreenAcres and also the very useful tool Pandora's Box. Save the building...
www.servuo.com