Well, that's not hard.
1)Install Max FX-Tools
2)Make a shortcut to RASMaker
3)Edit the path to read -x modname.mpm data
4)Open the shortcut
This will extract all of the files in a mod to a folder called 'data'
Now just edit away!
If you want to pack the files up again, do the following
1)Edit the shortcut to read -a data modname.mpm