Rear Pinion Seal is seeping slightly. Will eventually need to replace it. Dropping the driveshaft doesn't look like a big deal. Is it?

Questions:

1- Is a special tool needed to seat the seal?
2-Is there a spec. for the preload? If so what is it?

Shop I use when I don't want to DIY quoted $162.50 which includes the seal that only $25. I'm thinking with the preload needing to be set just right I might be better off letting them do this job.

For those of you who have done it yourself is it a pain and best left to a Mercedes shop?