There is an FAQ section, but it is mostly on how to use the site, set up user profiles, etc. Most answers/opinions/tips can be found using the 'search' feature. In this case the words 'seat pad' turned up several past threads:
Seat repair question
w124 front seat pads
A MBUSA STAR magazine article discussed the process in great detail (I may still have it around), and concluded it was easy to do, but difficult to do properly. But several members said they have done it and it isn't that difficult. If I were going to do this, I would spend the money for the new factory pad and/or springs rather than put in a towel, as the labor sounds like 3-4 hours, and the towel is likely to be an imperfect solution. I believe the parts are a couple hundred US dollars over hear, but may be lots less in Europe. Let us know how it works.
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
Click to see 87 300E