Just did this on my C280. It should be very similar to w210.
After much research, I used ACSource in Arizona. They were very helpful and all the items were delivered quickly.
http://www.acsource.com/index.asp
I strongly suggest buying a new compressor. IMHO, it is not worth the small amount of money saved to have anything else.
Parts bought from ACSource:
New Denso compressor
O-ring assortment package
Nylog Blue sealant for the o-rings
Pag-46 oil, 8oz, I used 2.5oz.
Bought the drier from FastLane - The MercedesShop Parts Store
Some folks remommend replacing the temp and pressure sensors on the drier at this time, I didn't. Time will tell if I screwed up.
Have a garage evacuate the system.
Disassembly is as described by gmercoleza.
I covered all exposed fittings with a small baggy to make sure no crud got in.
Reassemble with fresh orings covered with Nylog sealant.
Don't forget to add oil to the compressor before assembly.
Keep everything clean, clean, clean.
Finally back to the garage for evacuation and recharge.
My total costs for parts, supplies, and garage fees was about $900.
Good Luck, Dan