How about a logon script? You can use ASSOC and FTYPE in a batfile. If you
don't want to do this then you are probably going to be stuck with writing
your own ADM.
Yes, Using GPMC and tip 9808 » PolicyMaker™ Registry Extension freeware. in the 'Tips & Tricks' at http://www.jsifaq.com
If you don't know the registry entries, use assoc and ftype to determine them.