If you have an analog aux switch box for the time factor pedal, you can set one switch to tap tempo and chain it out to the 'rate' input on the murf. I have to do it this way, since I have the old murf. The factors receive TRS, but I think the murf receives on T-S for rate (not sure, going from memory).
If you're handy with basic electronics you can build a pedal or add a jack to an existing one. The alternative would be to use a "Y" cable out of the aux box (not a stereo splitter). like this one: http://www.hosatech.com/products/339659/Dual_14_in_TRS_to_14_in_TRS
