Within a function that gets called every frame you can get the tracker data as lists and extract the values you want to use. Something like the following:
Code:
def updateAvatar():
pos=tracker.getPosition()
ori=tracker.getEuler()
avatar.setPosition([pos[0],0,pos[2]])
avatar.setEuler([ori[0],0,0])
vizact.onupdate(0,updateAvatar)