Converting Direction Vectors In Children Manually

We're working with Leap Motion, which provides us with direction vectors for where fingers are pointing. Normally this works fine for things like drawing rays. However, when using an Occulus, all of the values need to be adjusted by the parent matrix, which is one of the Occulus parent objects. For drawing things it's easy, just put the game objects as a child of the Occulus parent camera object. However...we need to do the necessary matrix/Vector math manually for the direction vectors because the data doesn't account for the parent. Can someone help out with this?

Basically I need to know how to do direction vector adjustments using parent transforms manually that's normally done automatically by making the object a child of another transform. I'm sure it's just a simple trick but none of the matrix math I've been doing so far is working. Thanks! -Mike