First get a handle to the PPT tracker in Vizard via VRPN:
Code:
vrpn = viz.add('vrpn7.dle')
tracker = vrpn.addTracker('PPT0@hostname',0)
Then you can print the position data every frame or write it to a text file:
Code:
def printPPTData():
print tracker.getPosition()
vizact.onupdate(0,printPPTData)