UI work - qemu and key repeating

Was wondering if anyone has tried to use qemu to make a device emulator? I'm writing some UI/firmware and it seems like it might be a nice way to iterate on code. Also was thinking I would need to rework keypad.c so that I can get key hold/repeat events since I want to know when a key is being held down at some fairly short interval. Any suggestions/previous work/cautions? Thanks, Craig