I put mine in with the metal casing to the outside.
That's the way the original packing was installed, and IIRC, the lip on the new seal faced toward the inside that way as well. Check yours to see which way the lip faces.
There should be a slight chamfer on the housing so you can get the open end of the seal cup started in place. Definitely use a round pipe or socket the same diameter as the seal if you're doing in with the shaft in place. I did mine with the sector shaft removed and used a piece of wood to drive it in straight.
