Just done ! Here’s the serial debug output from the evaluation board. For technical details, it’s exploiting the iBoot USB exploit found in firmware 3.1.2 and below, and then jailbreak/boot the tethered device as Blackra1n does.
I only have my iPhone on hand, but it should work for all 3.1.2 devices (iPT2G, iPT3G…).

Since the MCU is only USB high speed, the operation can take up to 30 seconds, I’ll post a video as soon as possible. Stay tuned !