Not quite sure what all the fuss is about, I have found the best method that saves all the agro, I think anyway, get the comb before fitting the gaskets, place it in position by locating the two screw holes, then bend the comb down so that it fits flat against the top fin, sort of z shape, then get some thin welding mole grips and you can clamp the comb so that it does not move. Once you have done this, get the push rods so they are pretty much even, almost the same height, you can never get them all the same but as close as possible, then just put the gaskets in place, get the rockers ruffly in the middle of the rocker box, then gently let the rocker box down and if you haven't moved anything trying to get the box in position you should be about there, put in the four studs and screw down until you feel the push rods locate, just leave enough room to get the comb out, once this is done you should be able to feel through the cover holes, to make sure they are in the correct position, then tighten down not tight, to make sure, you can then turn the engine over to make sure they are acting as they should.
I have tried and tested this method, I hope it helps you.
Regards TTJohn