Instructions are the same for any single overhead cam PD engine.
I've tried both removing the tandem pump and not removing the tandem pump. Not removing the pump will make life easier and there'll be less mess from the fuel spill. Diesel fuel eats rubber and asphalt. However, it requires moving the camshaft and crankshaft away from TDC. To answer your question, the camshaft rotates once for every two rotations of the crankshaft so you can't rotate each 90 degrees or you'll find that it'll jamb.
Details and pictures are in the camshaft replacement article:
http://www.myturbodiesel.com/1000q/multi/camshaft-inspection-replace-VW-TDI.htm but basically, the advanced method of replacing a worn PD TDI camshaft is to:
1. put the engine at TDC. You can remove the fuel injector rockers now or later, doesn't make a difference.
2. Move the camshaft 90 degrees with belt on. The slot is now vertical. You can make a mark on the sprocket showing up, or make some general index mark to get the sprocket back on the same direction. This is not an acceptable final position for the timing belt, it's just to get the belt back on.
3. Remove the timing belt and replace the camshaft.
4. The sprocket has a key so it'll only go on the camshaft 1 way. Note the index mark you made before. Put the timing belt back on.
5. Rotate the engine 90 degrees back to TDC, remove the timing belt, and reinstall it the right way. Unless the timing belt was just changed, I'd also change the timing belt while you're in there. However, it's completely possible to slip the belt off with the motor mount still on.
I'll rewrite that part to make it more clear.