integrate rift + perception neuron (in unreal engine)

You don't want to disable the positional tracking off the Rift; that would be a disaster...the drift on the Neuron system would be way too bad. That and you'd end up with all kinds of latency issues without being able to use the ATW and ASW of the Rift.

In fact, the Rift gives you absolute positional tracking which solves the fundamental problem with the Neuron. What you should do is use the position and rotation reported by the Rift to correct for drift by offsetting the head sensor from the Neuron according to its position/rotation relative to the Rift head sensor...