not a lot of ecu work. actually, you use all the 2g computer...and just splice the CAS into the wiring harness. i thought the wiring was the easy part.

http://www.magnusmotorsports.com/1g2g.asp
that site has the most details on the current swap steps. leaves a lot to the imagination, but sign up for the 1gina2g yahoo email group, and they'll fill in the details.