You can't just splice for a 98 that I know of. The 98 ECU is a completely different ECU. You can (as some have done so) fiddle with the wiring harness of a 96 since they only have minor, pin0out related differences, but the 98 and 99 ECUs are unique each to themselves.
Plug the ECU in first and see if it works. I think it will. According to the pinout diagrams the 98\99 ECU are more alike the 97 ECU than the 96 ECU. My 96 talon accepted a 97 ECU no problem. There are only two minor differences in the ECUs.
Yeah, I was under the impression that the only difference between the 97 and 98 ecu was one or two pins. Check the Chiltons though, I could be wrong.
Avery
There is a difference between an argument and an assertion. This is an assertion: You don't want to fuck with Shady. The argument to follow: Because Shady will fucking kill you.
-Simon Stow, Professor of Political Science, College of William and Mary