Okay, confirmed that "0001" as the first 4 digits triggers an error message in SkySpy. It wants "7FFF". But I was indeed able to bypass that by entering the "0001" value for the TX60U sensor directly into the INI file.
SkySpy's mini browser is accessible on the network, and if I flip the GW back and forth between talking to the LaCrosse server and SkySpy, I do get a ping message when flipping it to SkySpy. Then, about every minute, it shows an RTC packet request, a ping, an RTC packet request, and a ping. However none of the sensor readings change to a non-zero value.
So they're "talking", but I'm guessing that the data types sent by the TX60U are not matching those expected by SkySpy for the C84612 weather station.
Back to the original question: has anyone yet got this working with the TX60U-IT sensors, as in the original thread post? Or are we on new territory? Very encouraging so far.