Reading OBD-I codes was easy. Just jam the paperclip into the diag port and watch the SES light blink. OBD-1.5 was the bastard child of GM. I've not seen many code readers that would touch it, especially 1994 +/- a year. OBD-II+ can be read easily by any of the available over-the-counter units. Most programming for the OBD-I/1.5 stuff was done with EEPROM burning, right?
I believe the reason GM came out with OBD-II was because they had to many problems with OBD-I not and the cost of having to replace PCMs with problems. Because OBD-I PCMs where like CD-Rs write once. This was killing them so they came up with the new memory to allow PCMs to be reflashed by dealerships.
I'd check out TunerPro. Its free for the software and I believe should work for you since you have a 95. TunerPro and TunerPro RT - Professional Automobile Tuning Software (<--- Click that, doesn't show up as a link with the new skin)
In the definitions, you'd need the $1FA bin file.