Yeah, my pally isn't close to geared as well as either of those. He can pull walking backwards well enough, but the trouble is getting him to take down 80% of the mobs health BEFORE the mage gets booted out of the instance. He just isn't geared well enough to do it, unfortunately. What I've thought about doing is use all 3...have the pally pull, the priest leave group when he gets to the entrance, have the mage aoe 1 time, have the paladin leave the zone, and see how that works out, provided the pally does NO damage.
Regarding Holy Nova, the priest just hits me with Renews and regular heals while I aoe on the mage, so he builds enough threat that way.