Sweep vs time at constant frequency - 4294A Analyzer

Hello,

I am trying to change the mode of measurement on our 4294A impedance analyzer from taking a measurement of impedance vs frequency (from 40Hz to 10MHz), at 5mVac constant bias, to taking a measurement at one frequency over time.  I would like to monitor the change in impedance vs time, at say 100kHz and 100mVac.

I tried to put the analyzer into "zero span sweep" mode to take data at a constant frequency and AC bias (as per page 94 of the user's manual), but wasn't able to actually start the measurement - on the oscilloscope the 4294A was still scanning the previously setup frequency window.  

Anybody familiar with this mode of use?  And how to switch to constant frequency mode?

Thanks!

James