Output shaft oil seal (manual C-class W203)

I have a very minor gearbox leak. I have had a german autos independent look at it, and they have suggested it is around the 'rear seal', but claim they would need to take the box off to have a proper look. The technician suggested if it was his car, the leak was so slight he would leave it until a clutch change was due.
Having recently aquired a Haynes manual, the procedure for changing the output shaft oil seal, on the back of the manual box sounds fairly simple (I only checked the details on the manual box, so can't comment on the auto). It strikes me that the 'rear seal' and the output shaft oil seal are the same thing. For replacement, essentially:
(i) the drive shaft is disconnected from the output shaft.
(ii) a special or make-shift tool is fixed to the output shaft to allow it to be held still
(iii) in neutral, the shaft is held and a fixing nut is removed
(iv) a plate is removed and the oil seal is prised out
(v) clean and refit as reverse of removal

Whilst being very mechanically savvy, I would not tackle this myself due to a sincere dislike of wriggling around under the car. However, this seems a quite likely cause of the oil leaking, and doesn't sound to me like the box needs to be removed to carry out a thorough check in the first instance. This sounds like a quick, cheap likely option to try first. Providing I can find someone who doesn't was to take the gearbox of to do it.

Thoughts please?