If you are applying a uniform gain to the data, then you can use the filter plugin. Here is sample code that creates a tracker object with a 2x gain in the x,z axis:
Code:
filter = viz.add('filter.dle')
magnifiedTracker = filter.position(tracker,scale=(2,1,2))
view = vizcave.CaveView(magnifiedTracker)
However, you should not be applying the magnified data to the frustum calculation, only the viewpoint. The frustum still needs to be computed from the physical eye position of the user, even if you are simulating a longer stride.