Well, having the menu hotkeyed would require a program that interfaces with the menubar/WM (eg, Fluxbox's fluxbox-remote) or some WM hotkey file (eg, ~/.fluxbox/keys). I don't think JWM has that (I haven't looked recently, though), and I have no clue about IceWM.
The silkscreen keys are another thing altogether. I believe Angstrom supports them, so if you use their kernel, they should at least give X events. From there it's just a keymapping process.