I tried to do just that when i replaced my water pump and realized that my belt tensioner pulleys were rattling when i spun them by hand.
I did not have much luck with it though. No matter how delicately i tried to pry those rubber seals/flanges out, they got deformed to the point where they most likely would not seal anything anymore.
I ended up replacing the pulleys with new ones.
So.. how on eath did you manage to get those seals off -and back on again without damaging them?