Trouble getting 1997 jimmy SLt into programmable mode(key fob)~

I purchased a used keyless transmitter and cannot get my jimmy into programmable mode. I tried this process; hold unlock button, ignition on/off/on/off, let off unlock button.

I tried this many times and it never worked. I looked into another way involving removing the bcm program fuse which my car does not have.
Are they any other ways to get it into this mode? What am i doing wrong?

I had the exact problem. I finally found what you need to do. Look for the test plug underneath the dash. You need to find a good ground. Then connect a strand of wire between the top right terminal (I think it is identified with the letter A or B - you need the top right hand corner one) and your ground (screw or metal), you should hear the locks jump up and down. This will tell you that the vechicle is in program mode. When you get to this point I am not possitive but I am pretty sure that I had to hold down the lock & unlock buttons at the same time. Your original remote should already be programmed, but this will program up to 4 remotes.