Probably not a good idea on a scope but for future reference, if you ever have an allen wrench bolt that the head is stripped and it's standard measurement, grab the next size up in metric and tap it into the bolt with a hammer or a driver of some sort. The wrench should make it's own new hole. If it's metric take the next step up in standard. The vibration and everyithing probably wouldn't be good for the scope, but just for future reference.

If the head of the bolt sticks out a little bit get a pair of vise grips and latch onto it and get it turning even if you can only get it turning with small turns. After a little bit you should be able to use the allen wrench again. The bolts on my scope stick up just slightly. Obviously, I don't know about yours.

Also, when you're done, it should go with out saying but, get new bolts that aren't stripped.