I was going to say thats a dangerous thing to say on here, lol.
If he works on cars anyway and has half a brain he should be ok. Two things that normally lead people to have mistakes are
1. bin the transport nut thats holding the front strut/coilover assembly together, you dont need it when its fitted to the car and it tends to confuse people.
2. use all the parts off of the OE strut from the upper spring plate upwards (bearing lower rubber mount brass spacer shallow nut etc) and in the same order as they are used on the OE strut. Thats about it and you'll be fine.