For the northern section from Grenoble to Geneva/Thonon, you can find informations from the following site :
http://www.openrunner.com/Unfortunatly, the site is only in French. But maybe you speak French ? In this case...no problem!
If not, you can proceed in this way :
Trail number : 1256961 (write this number in the case named "rechercher des parcours") From Grenoble to Chamberry
You can unload the GPS file.
You can find many informations on the other web site :
http://www.utagawavtt.com/randonnee-vtt-gpsFor the routes between Chamberry and Thonon, click on the "rechercher" button after having clicked on the combo list "Dept" and informed "Haute Savoie"
You can unload the GPS files too.
I did the route few years ago, but in the other direction, from Annecy to Gap. I can give you the track if you want to.
I'm not sure my explanations are very clear, I can help you if you need more informations.