Neil,
We are actually trying to get a development device of the GDL-39. Theoretically it should work as they even offer the bare-wire connection cable. The GDL-39 comes in two flavors, one wireless and one wired/wireless, according to the Garmin site. The wireless only will not work as they only use Bluetooth. The Wired option may be possible, we'll know more once we can connect to a device itself.
Many people are struggling to see why Garmin chose to only use Bluetooth and not Wi-Fi. Wi-Fi is such a more powerful signal and handshakes much better for a more seamless connect. Bluetooth often needs re-pairing. We'll know more in the near future as to GDL-39 integration. I hope this helps.