I did it during an internship back in the summer of 2009. It took a little bit of practice but I got the hang of it pretty quick. After a couple hours I was able to get a node grafted on fairly quickly and about 90% of them took to the vine, if I remember right. We were grafting chardonnay onto winter hardy vines for research. Unfortunately I don't know how it all turned out but having done the grafting in May, the buds were thriving like crazy by mid to late summer.
I am going to try again, this spring, to graft Merlot to DeChaunac. Was not successful last year with any taking. Go on Youtube there are good videos on how to do it. There are a number of ways. The trick is getting the to scab over. Mine kept dripping sap no matter how hard I wrapped them and cut below the graft to release the sap hydronic pressure. I think I cut too deep. You only need to cut below the bark layer. Cutting too deep does not help the bud get the sap. Good luck,