I don't think remote was avail on 88. my 91 manual does not mention it, and my 90 parts car don't have it. I think it was optional in 92.
for the factory code look inside the trunk, on one of the hinges for a label with a 5 digit code (usually right hinge). that is the permanent code for the keyless. if its not there, look at the controller itself (located in trunk, on backside of rear seat back, hidden behind the carpeting). the code will be there also.
a couple quick things it does...
pressing 7/8 and 9/0 at same time locks all doors.
after entering the keyless code, pressing 5/6 will open trunk, 3/4 will unlock other 3 doors.
there are other features that you really need manual handy to program... like a 2nd 5 digit code, how to turn on/off 'autolock' (where it locks door automatically when you move shifter thru the 'R' position) and maybe a couple other things (actually they are not hard to do, I just don't remember the sequence off hand).