Assuming you've got a 722.315 (or a 722.303) installed in there (as you should have) you can see what to do in these threads =>
722.315 Pump Re-seal pictures
722.303 in bits photo shoot
To remove the transmission there are two schools of thought =>
1) Try to just remove the transmission by itself - so disconnect prop shaft - lift the car - remove transmission etc
2) Remove the transmission and engine together in one go
Option 2 does sound totally bonkers but in my opinion that's the way to go! The benefit is that you are less likely to damage the transmission when you are mating / de-mating it to the engine. To remove the transmission by itself I think it is safest to do so if you have a decent lift and a transmission jack etc. As a DIYer with axle stands and trolley jack(s) I think it is a bugger of a job to attempt option 1.
If you are entertaining option 1 I've written this which might help
How I took out my 1981 W123 300D (euro) non-turbo engine
You can see links to parts and parts lists via the second link I posted above.
Timing wise I reckon you're gonna loose about one weekend if it all goes well.