It's not a simple project to swap to a manual transmission. There is a thread somewhere describing what would have to be done. A few things I remember would be:

1. Change the brake master cylinder reservoir to accept the clutch hydraulics.
2. Change the brake/clutch pedal mechanism.
3. Make sure you get all of the shift linkage and install a new center console plate (wood or plastic to accomodate shifter).
4. You'd also obviously need a tranny.
5. You'd need to verify that the drive shaft lengths are the same (not sure).

It seems like there is more, but this is all that comes to mind. It would not be a simple swap - you'd probably need a donor car to do it economically....otherwise, you'd be better off just buying a manual transmission car.

Good luck.

__________________
1976 240D
1987 560SL
2007 E320 Bluetec
1998 C280 (now son’s car)
1982 240D Manual - Sold