Easy peasy - 10 or 20 minute job. Change it from below. An 8mm 1/4 inch drive socket and ratchet, medium sized hands and a willingness to get dirt and grime up to your elbows are all that's required. Removing the plug from the FPR makes things a little easier when you're connecting the new CPS.
It's just to the rear of the starter and can be seen from underneath if you remove the acoustic cover and dangle a light down behind the inlet manifold.
Undo the single bolt holding it in and take it out, from above fish it out, unplug the dud and plug the new one in and dangle it so you can reach it from below. Feel around until you can get it and the bolt into their holes and retighten the bolt.
Done, beer time...