So, are you just needing a "log" option within the impedance analyzer? If so, then I would suggest to modify the impedance analyzer source code to write the data to a spreadsheet file.
The source code VI for the impedance analyzer can be found within the ...\Program Files\National Instruments\NI ELVIS 1.0\Source Code\Impedance Analyzer directory. You could add the Write to Spreadsheet File VI to the program to create a VI that would log the data to a spreadsheet file.
I hope this helps.
Regards,
Todd D.
NI Applications Engineer