[SSLance]

I've never used that particular setup, but from just in general seal setup, they are a bit tight going in usually because of the coating around the outside edge that seals them against the housing. If I remember the tapered bearing setup correctly, the axle and bearing are already in place when pressing the seal into the housing, correct? Doesn't the hub make it difficult to get any real pressure onto the seal to push it in? I would think using the retaining plate to push the seal the rest of the way in is a good method...

The only issue might be if there isn't enough room inside the axle end for the seal to fit, you'll end up crushing it. Can you measure everything before putting it in to make sure there is enough room for it to go fully in without binding or crushing?