There is no support for proxy mounting in the Control Panel applet. I would say that it would be better to build some other kind of GUI for more advanced features if we want a GUI tool for proxy mounting somehow. Control Panel applets are a rather outdated concept for administration of drivers and system services anyway these days and they are increasingly difficult to support for each new Windows version.
As a developper,I fully appreciate that it is tough to decide to implement an extra featture or even "simply" rework the GUI.
What may appear as a simple GUI matter for end users ("oh it's easy! just add a radiobutton!") many times mean a complete rework of the logic, the function signatures, etc ...
Actually, this is a discussion we often find on this forum around dev guys "challenged" who are challenged to change this or that and related to that discussion, Wonko actually use a word for that : Featuritis
CloneDisk or Tiny PXE Server many times gave me cold sweats when I found myself engaged in a change which meant afterwards a complete rework of a unit...
Now, just to take one last chance ... what about "only" (shamelessly minimizing the effort there to increase my chances) introducing an extra device type in the GUI named "proxy" (next to harddisk, floppy, dvd, etc) and allowing the user to enter the proxy details in the filename field ?
Is not this what we are doing on the command line? specifying -t for type and -f for filename?
Dont get me wrong, I am a huge fan of Imdisk and DevIO and these two already do lots more than I need so they are already just great as they stand today