Can you describe exactly where you're having trouble? The video we did shows which orientation to use for the angle plates if you're using two pedals for the RS Pedals as well as how far apart the pedals should be on the heel plate. Attach the angle plates to the pedals first and then add the next section of the angle plates, finally attaching the bars which attach to the main seat.
That's the basics - all you're really going to need to play around with a bit is the fine tuning of that first part where you attach the angle plates to the pedals. There's a bit of leeway in the sideways directions due to the fact that the slots you bolt through are just that - slots, not holes.
