You should be able to remove the sprockets several ways:

1) use an impact gun
2) wrap the sprocket with a length of old timing belt, grip the belt with large pump pliers to stop the sprocket from turning
3) insert a large screwdriver or bar into the sprocket and brace on the head area

For installation methods, use #2 or #3 above.

Frank

'89 [color:"white"]G-Raider[color:"white"] [color:"black"]Supercharged 3.0L, MegaSquirt 2, lockup A/T, 2.5" exhaust, 172k, Cibie H4s/Oscar SCs, Hella Micro DE fogs, Cobra CB, Superwinch hubs, LSD rear/Aussie Locker front, Bilsteins, Lifeline AGM, Rust-Oleum