Hikertrash, WOW! The "tool" is nothing more than what is called a "tamper proof torx" bit. They are a commonly available tool. I just don't know what the size is for the Montana, but a trip to Sears or anyplace that has a good tool selection where you can test the fit should do. When I have a reason to go to Sears, I will see if I can find the size and post it.
Mudcat: You could do that. But, the way the power cord kind of snaps into the AMPS Rugged Mount, it might be a little fiddly to deal with every time. I haven't tried it yet, but it might be easier to deal with loosening the security screw, you'll have to try and see what your preference is.
I don't keep my Montana or Zumo in the mount all the time because as long as it is in there, it is charging the battery, and I don't want that constant(?) drain on the bike's battery.