Since the 6VE1 is a non-interference engine you at least don't have to worry about bent valves. The timing belt removal/replacement is pretty clearly outlined in the shop manual, including the timing reference marks.



Number 8 on the diagram is a blow-up of the reference marks for the camshafts, numbers 2 and 5, while number 7 is a blow-up of the timing mark for the oilpump shaft, number 1. All three should align to those marks.

Also note, from the manual: When timing is performed, the number 2 piston will be at TDC.

When changing the timing belt the battery should have been disconnected (for safety) which would force an ECU reset as well.

Check your timing against the reference marks and let us know your findings. Good luck!