You will have to make sure that you cut the end of the throttle tube off and remove all burrs from the internal side of it. Make sure that you leave the throttle loose when installing the hand guard. After the hand guard is installed, position the throttle so there is a small gap between the end of the tube and the hand guard so it does not rub. After doing this the throttle should move freely and not stick.
Unfortunately any hand guards with mounts for a Pro Taper bar, are not going to work with Easton bars as they taper at a different rate. With Easton being so new with their own bars, there is not a huge aftermarket following yet for accessories like Pro Taper and Renthal have. The easiest solution would be to use a set of the Cycra Pro bend guards, with either the 1 1/8" u-bolt style mount, that give a little more flexibility in the sizing of the bar, or their triple clamp mount that doesn't even rely on the handlebar to mount.