Here's the factory procedure to adjust the bowden cable (first section, OM603.96) :
http://www.w124performance.com/docs/mb/W124/trans_Bowden_adjustment.pdf
And here's the procedure to replace the cable - you have to drop the tranny pan to do that:
http://www.w124performance.com/docs/mb/W124/trans_Bowden_replacement.pdf
To locate the converter drain, you need to slooooowly turn the crank by the front 27mm bolt. After you find it, use a white/yellow paint marker to mark the balancer so you can easily turn to it in the future.
There's another 3 quarts or so in the converter.
Here's the adjustment procedure for the vac control valve, on the side of the IP. Note that it's a right/wrong setting, not a variable adjustment. (Trust me on this. BT, DT.)
http://www.w124performance.com/service/w124CD1/Program/Engine/602_603/07.1-1826.pdf
