Probably a little late, but I'll add just in case someone else ever needs same info.
Spent the weekend replacing both front doors on daughters c240 because of rust. Bought the car with rusted doors and found 4 matching doors locally.
Instructions posted on this site were perfect.
After removing the 3 screws securing the lock and the IR or locking cylinder, the locking mechanism must drop and rotate about 90 degrees then lowered out of main access hole. There will simply be no room to remove it with the window and regulator installed.
Some rivets will be easy to drill out, others are a weird type of flared rivet that had to be ground off with a die grinder.
If using a drill, heed the caution regarding drilling out rivets with glass installed. I did punch through one rivet and nicked the glass; luckily no breakage.