After one week of trying we give up to create a UDK Version of our UT3 modification. There are to many problems and we would have to rewrite nearly all scripts and correct every map, many matinee sequences and Kismet events. Because we are neither planning to expand our mod nor have so much time at the moment we decided to stop it.
Currently a new project is in development. But we do not use the UDK.
To bad. Would have been quite something, but maybe its better this way.
I can not believe you have to rewrite all scripts. Maybe write some scripts that where default in ut3...
About the map, there is a really good way to do it. I ported Shang-ri La to UDK within 2 days with all meshes, brushes, events working properly.
Good luck with the new project ;)