Get/Set DOS Master environment values.

Not having much luck with this one - no error, but dose not set properly either.

A little project based on the FreeDOS kernel, I need to set DOS environment values, and not just that programs, the master environment - so if you enter TYPE at the command prompt after running that program, you will see the change. For some reason, I could not get this to work even with INT 2E, but really I would prefer to do it with 100% self-contained code anyway - and really should work for any command interpreter shell.
Basically, I need to do in assembly what ENVIRON$ dose in Quick/FreeBASIC.