(assuming it's an oem or oem-type distributor) There's a screw holding the rotor to the distributor shaft, you have to crank the motor until you can see the screw facing up at you. To be on the safe side you can remove a single plug wire (from the cap) and put it on the end of the coil(or just put the cap back on), otherwise keep the cranks very short if you crank the motor with the dist. cap off, otherwise you could overheat the coil - it's unlikely unless you really crank, but better safe than sorry).

Also, they can sometimes be on there real tight, so make sure you get a screwdriver that fits well into the head of the screw, and use plenty of pressure so you don't strip it.

edit: fixed it, I was in a hurry and apparently not of sound mind when I typed to remove the ignition coil before removing the rotor h: (not possible on most cars b/c of "dust cover") I meant to remove a single plug wire and put it on the end of the coil, if you have to crank it more than a split second w/ the cap off.