I don't think you can re-use them, as they are pressed in and must be pried out.
Haynes describes this and it's pretty easy. If you are going to be a DIY'er, you should pick one of these up. You can find them at Pep Boys or any parts house.
To remove the seal once the rotor is off: Use a hammer and chisel to deform the seal. Then pry it off with a big screwdriver. Remove all the old grease. Grease the inside of the seal, place it over the opening and place a large(same size) socket over the seal and tap it into place.
91 300E 120K
90 300SE 275K (sold)
92 BMW 525iM 120K
90 BMW 525iA 175K
85 300D 175K (sold)
84 300SD 245K (sold)