ULX has no feature to do this by default.
A module could be written by someone else to do so though.
You may try tinkering with the per-map cfg files that ULX can use though.
See the example addons/ulx/cfg/maps folder.
Any <map_name>.txt file will get loaded after the <map_name> loads.
Problem is, I don't think you can change gamemode after a map has loaded.
Our ulx map command includes a second parameter <gamemode>, but again, I believe that changes/loads before the actual map does.
(Remember, don't actually edit your /addons/ folder... if you modify cfg/maps ... put it in gmod/cfg/maps)
I don't know if any of the features are working in SVN ULX currently.
