I'm not familiar with the Vive vamera rig, but it's important that the LeapHandController Prefab be in the same position as the Leap Motion Controller is in the real world. Have you applied an offset from the eyes? (For Oculus, this was 8 centimeters.)
We've played around with this as well, and have found that the controller models aren't quite right for Vive Pre. Altspace now supports both at the same time, and as you can see it's not quite perfect.