Yeah… FFC Centres are all over the place in France, generally on ‘existing’ trails which are mostly all open access over there.
Some of the Peille routes are on their website:
http://www.peille.fr/index.php/sports-de-pleine-nature/v-t-t
Unfortunately, the FFC website doesn’t give you the trail maps. Those have to be picked up from the local Tourist Information Office and are usually pretty naff and need to be backed up with IGN maps. However, if you’re lucky, some kind soul will have put a GPX of some of the trails on a website somewhere. Again, http://www.vttrack.fr/ can be useful in locating them.
If you want to know where the FFC VTT centres are, here’s their web link:
http://www.ffc.fr/a_VTT/a_SitesVTT/index.asp
The “Grandes traversées” (“Major Crossings”) link on that page will take you to a list of eight long distance point-to-point routes.