Hey twisteddragon.
Under the hotkey editor, at the bottom of the list under categories there is a category called 'user' that you can assign custom commands to your own hotkeys. If you just select the user category, you can enter a name and description for your new hotkey, then input the commands that will run when you press it. The command for convert selected to poly is TesselateSubdivSurface; I think (I tried it out and I think it worked properly). Then just accept the new commands, and assign a new hotkey like normal.
Hope this helps.
LisaG