You can always go with the MS1 and later upgrade to MS2 RS-autosport are releasing a daughter board with MS2. There's only a few 420a's running MS2 right now you can find them on Neons.org. Heres a link to the wire diagram
http://www.rs-autosport.net/catalog/..._Super420A.pdf If you have all the diagrams you would be able to get it done in a day. Only thing you would have to do, besides the wiring is welding the IAT sensor bung in and figure a way how you want to mount the watertemp sensor.
Edit: Just realized Rs-autosport does not make the super 420a and more so use this
http://www.rs-autosport.net/catalog/...iring_420a.gif