The instructions you get with it are pretty good, I fitted mine OK.
If you are not changing the MAF from Bosch to Pieburg then use 1-5.
I found fitting the Ronbox pretty simple, getting the air filter housing back on a bit annoying (but then I had practice from a Rover 75 with the same engine). The in cab switch though was a complete PITA which even left me having to go to the physio to straighten out my back...