Use a jumper wire I think on the top two pins on right side of the ALDL port. Count the flashes after the first five of the ses light- the times it flashes is your code- when it flashes five times for a second time the codes are done.
Easiest way IMO is just get a small or medium sized paper clip straighten it out and then bend it into a "u" large enough to fit the upper right two ports on the diag port and just leave it in the ashtray or console. Jump the upper right two ports and then turn ign key on no engine start and count the flashes...first flash should be the code for the ECM being good and after that will be stored codes for whatever.