Change "kAccelerometerFrequency" at runtime?

I have been doing some optimization lately, and I am playing with tuning the main loop, as per cited in this documentation page:

iPhone Optimizing MainLoop

I changed the "kAccelerometerFrequency" to a lower value, but I would like to set it to 0 when I don't need the Accelerometer, for example, when using touch controls instead of tilt controls.

Is there a way to change it at run-time? Thanks for your time! Stephane