A couple tricks to installing the one piece seal on a Lycoming:
Have a microwave handy to heat the seal in some hot water for 5 minutes or so.
Put a plastic baggie over the flange and give it a good coat of oil
Use a long 3/8 extension with a a nice, round polished shaft to work the warm seal over the flange.
5 minutes.
The real trick is safety wiring the prop bolts. That takes a bit of finesse. Depending on the prop, you may need to make a special wrench to get the bolts off.
Oh, and if you have an alternator, perfect time to replace the belt.