You could try something like the following to place the viewpoint just above the origin. This code is assuming the tracker coordinate system matches Vizard's:
Code:
#get pos of tracker when script starts
pos=tracker.getPosition()
#link view to tracker
trackerLink = viz.link(tracker,viz.MainView)
#apply postTrans operator and negate x,z values
trackerLink.postTrans([-pos[0],pos[1],-pos[2]])