An ice cube relay is a simple single pole double throw relay used all over MB cars. There's a bunch of them in the relay comparment of the fuse box. It's so called because they are about 1 inch square and made of bright silver metal - they do look like an ice cube.
I don't have a wiring diagram handy, and I'd be a bit reluctant to post it if I did. Here's why. As SteveB points out in another related thread, some cars use a ground signal to indicate compressor on, others use +12v. You need to determine which your car uses and wire up the bypass appropriately. It's a simple task which requires only a DVM. However, if all this is beyond you, then you're probably best off not going there.
Sixto - I noticed that while I had the bypass in place that kickdowns did not work, at least not all the time. I think the full throttle signal causes the Klima relay to both disable the compressor and signal for a kickdown. It's certainly something you can live without, but is nice to have.
Brake parts cleaner shoud work just fine. Just saturate the clutch air gap. I think I used Simple Green followed by a good hosing down. Either should do the job.