Another method to hold the seal "in place" is to pick up some "O" rings that will fit over the pedal spindle and fill the space between the seal and the arm (or the spindle's flange as it butts up against the arm). This is how the Stein BB injector kit sealed the BB cups, the "O" rings fit between the cups and arms in this case.

I've long thought that the pedal bearings are the most abused and neglected rolling parts on a bike. Who does pedal overhauls any more? At work I've done, maybe, a half dozen over the last 10+ years. I will often inject grease into pedals that allow it without much effort (like the Look/Shimano spindle/cartridge designs). I don't call this adding lube an overhaul though. Andy.