I made the same tests on the Line 6 XD-V75 receiver with TBP12 beltpack transmitter. The cable for the beltpack: XLF pin 2 to TA4F pins 3-4. XLF pins 1-3 to TA4F pin 1. TA4F pin 2 unconnected. The big downside is no phantom power like the MIPRO plug-on has.
I built the above setup with an XD-V55/TBP12 today, and it seems to work. I'll run some better tests over the next few days.
The only battery phantom supplies available locally were serious brand name offerings that were $400+, so I am using a simple circuit with 2 9v batteries. My measurement mic is the dayton emm-6.
I am using the Studio Six package on an iPad as a single channel TF rig. This has worked fine for me wired. Wireless should be a nice enhancement.