hang on... he said he wants to work in the summer... there aint no snow in the summer, so no point telling him about all that stuff.
Anyway, I have worked as a guide in the summer (in Morzine and surrounding area) on UK qualifications, and keeping an eye out for the police. That was in 2007, and it was a bit shady to say the least.
At the moment the situation is that they really really reallllllllllly have cracked down on it, and no one is being foolish enough to guide in France if they only hold UK qualifications. So basically its out for next year (the French qualis take aaaaaages to get, like more than 2 years I believe). Lsat year the highest qualified british guy (he had UK guding qualifications and a mountain leader qualification which the french do actually recognise) in Morzine got arrested along with one of his employees who holds the SCU SMBLA guiding qualifications (which they don't recognise). It went to court and the French court gave them both minor records. However, apparently the european court will now take it up for them and fight their corner, so hopefully things will change in the future and the French will recognise the UK qualifications, just like every other european country does. But for the time being they don't.
If I were you I'd try and base yourself in Switzerland or Italy because they do recognise our qualifications, and before that you need to get yourself on the SCU website (
www.scu.org.uk I think) and look up the info about the SMBLA qualifications. You'll have to do trail cycle leader first (TCL), then do Mountain Bike Leader (MBL), which is what you really need to guide in the mountains as TCL only qualifies you up to 600m on "non technical" terrain, so that rules out the whole of the alps! But both of those qualis are relatively easy to get assuming you have a first aid cert (but that's easy to get), and are a fit and able rider, which I guess you are!
Alternatively get on the chalet hosting wagon instead and then you're able to look for work in France.