[gnomic]

Man, some people just aren't happy until thier beer is really, really cold!

I think google books has a book on cyrocoolers - which is what I think you are looking for. You can achieve this by stacking cyrocoolers. NASA, JPL, and Los Almos have posted some research on the subject. If power inputs, time, and cash aren't a problem, you can probably do it. If you have access to some liquids like He@ N2 or even CO2 you can probably cut a few corners. Of course at 4K, you are going to have issues with your materials. do a keyword search on cyrocooler and see what you come up with.