You need to get the engine to TDC. This is found by looking into the engine through the oil filler and you will see HT cast into the cam. This should be just starting to go down to the right, you then need to insert the crank locking pin. If the pin will not go in you may need to rotate the engine one turn.
This process is easier with the front lock carrier, rads and engine covers removed
You need to lock the crank @ tdc with the correct pin. The hole is located behind a plastic blank on the block to the rear of the aircon pump,
You then need to remove the vacume pump on the rear of the r/h head to reveal a keyway, you will need to slacken off the cam pulley to insert the correct flat tool. On the right head you need to remove a plastic blank, this will reveal the same keyway. Using the two key way tools with the pulleys loose, align the cams. You then need a pin for the tdi pump, once the cams/crank is timed the pin may slide in if not you will need to slacken the three bolts securing the pump belt and adjust. You should once correct, tighten the cams remove the pins, rotate the engine for two/three rotations re-check the timing and repeat if out. You should check the pump timing on vag-com via the TDi graph for the optimum.
I have the correct tools for sale here.