Gerry
I went to the alps last year and we hired out some small trail bikes, there was loads to ride and 90% could be done on a GS.
The year before we ran into a group of UK TRF guys that were doing a 2 week trail ride in the area, and I believe that a write up appeared in the TRF Mag shortly after, I'm sure that if you contact the TRF they can point you in the right direction.
Simon
P.S This was in the French alps near Briacon and the border with Italy