We did it a few years ago, great fun. One of the best races I've ever done.
We tied it in with a few weeks of riding in the alps and got off pretty lightly.
I would stay 3 days either side of the event (Wednesday to Wednesday would be ideal, then you have time to ride the other tracks afterwards).
A 6" bike would be ideal for the race itself (maybe a Reign/Remedy/Nomad with 160mm forks and big brakes)... BUT, for the rest of the riding holiday, a DH bike will be a lot more fun, especially if you head to le Portes du Soleil. It's a good idea to take spares, as conditions are brutal and spare parts are expensive.
We organised race insurance through the Megavelanche organisers (Active MTB maybe? can't remember), although I had my own travel insurance through flight centre.
PM me for more info, otherwise I wrote a piece in AMB a few years back about it.