Could someone inform me how to replace an AC Compressor Clutch on a 1984 300D Turbo?

This morning, the local Mercedes Shop inspected my entire air conditioning system and said that the compressor clutch was not operating. They informed me they could not order or replace this one particular item, but could order the entire compressor, receiver/drier, expansion valve and recharge the system. This would be very costly.

I have read through the threads on the message board and noticed that some people have replaced the clutch, but I could not find any specific information about the process, tools, or how they did it.