I been thinking about giving something like this a try with the nokia charging plate (DT-900). It appears to be one of the few qi chargers that doesn't look like you're setting your phone on top of something the size of tablet (which is probably great for the nightstand, but not so great for turning into a car mount). The nokia is smaller (length and width) than the n4, and the voltage it expects from it's wall wart is already 12V.
I also picked up a generic "universal gps car mount" that looks like it would be easy to attach things to. I still need to find something to actually hold the phone in place, but that should be fairly straight forward.
The real issue at the moment is that the phone does the connected-disconnected-repeat cycle that has the lg pad owners tearing their speakers out (fortunately the nokia charger doesn't have a speaker built in). Since this is happening with multiple different qi charges, hopefully it's something that'll get fixed in a software update. That's assuming that qi isn't just a complete outright face-palm.
Which brings up an interesting question, are we going about this all backwards? Like many others I've been hoping that someone will find a way to stuff the guts of a qi charger into something like the touchstone. (Great work terracode, I'll be keeping an eye out for more on that.) But with the touchstone-esque google charging orb having no indication of being anything more than vaporware, and with Google officially joining the qi-competing PMA (apparently announced the same day they announced the nexus-4), perhaps we're doing this all backwards? If qi isn't the universal wireless charging standard of the near future (and so far I'm not impressed), perhaps the thing to do is replace the qi coil in the phone with a touchstone compatible one (and associated magnets) much like the galaxy nexus mod.