So as it turns out, HPTuners CAN interface with the PLX controller with a factory style cable.
The cable I put together was imitating this one:
http://forum.nistune.com/viewtopic.php?t=2555 and should also produce the same results as the factory PLX USB logger cable.
The solution came in the form of a software "hack" which is described
here. Pretty much you use VPSE to create a pair of virtual serial ports, then use his converter (which converts the PLX iMFD data stream into the AEM UEGO format).
I then added an AEM Air/fuel ratio channel in VCM scanner, connected, started scanning, and it popped right up!
working.jpg