Everything for the 97-99 works except the INTENSE PCM. But the DHP works with it. So basically it'* all good.
Despite the higher ratings of the S2 L67, we have yet to see a 96 SSEi have trans problems with the 4T60. In effect, since the S2 doesn't develop it'* peak torque at the low RPM'* of the S1, the trans isn't under as much stress.
There are rebuild kits available for the 60, as well as a GREAT shift kit. I've had a bulletproof 60 built for mine. The entire saga is posted here. The 60 also doesn't have the same 'typical' problems that the 65 do, and they tend to last longer before the first intervention than the 65'*. We have a poll on this where we collected data for quite some time.