I've seen a few freezer conversions done, and there is a thermostat link posted here which takes all the brain work out of it. I have one, but it's not used for beer, it's still a freezer, so I see your point about loading full kegs into it. Pony, Half, etc. wouldn't have any issues, but a full keg, that's going to require some help.
The alternative to that, because I'm such a fan of the freezer conversion is a stand up chest freezer. That, you can easily stack full, half, or pony kegs, and won't have the issue is loading them in and out, and has a smaller footprint than a top load chest freezer.
Here is the quick and easy thread on the device to buy to convert:
Specifically, this doodad right here: http://www.northernbrewer.com/brewin...ontroller.html