You don't need a harness. Just the connector and 5 more pins to add to the pcm connector. 97 wasn't such a bastard year. 97 was the first year of the 4T65 on the S2 SC. 96...that was a bastard year for the SC S2 and 4T60, the pcm had a smaller file etc etc than even the 97.
You can swap just a trans w/o doing the whole wiring harness though. There's a how to on it.