Unzip the Houses.zip file, then move the houses.MAP file into the UOAM program directory.
Inside UOAM, go to Places > Edit or Go To Labels > Files tab and put a check next to Houses, then the locations will appear on the AutoMap.
I've got most of the houses mapped now. I'm sure there are some on islands and other remote places that I don't have since you've got to visit the location to add the house.
Map > Additional Settings > UOAssist tab
Be sure the top checkbox is checked (Show objects...), and set Log Houses... to "Houses"
When UOAM adds a new house you've got to right-click and edit it to add the owner's name. Also, it doesn't remove houses that were demoed since the last time you were in the area. You've got to right-click and delete the marker manually.
Thanks Yordor!
GhostRiderGrey