In case it helps, anyone, I've created a google map of the route I take from Elland Road (M621 J2 roundabout) to AMF Leeds. I used my TomTom to help me create this route having got stuck on the A58 beyond the point I now turn off or leaving the M621 later (J3) and then trying to get into town passing the Station.
Although there's a loop and you appear to go a long way out of your way, it saves time!
This link should take you there:
http://maps.google.co.uk/maps/ms?msa=0&msid=112982385461377190219.00044d095db7b669d74a8
Hope it helps cut down on your journey time, when you've got to Leeds. Can't help with the rest of the M62, sorry...