As the source code is not available you can't change it and recompile so your only option is to edit the .hex file directly. To test this idea I loaded the controller firmware (should be similar enough) in a hex editor and searched for the string "Soarer" but it was not found so that's not going to work.
Since the firmware is provided in a .hex file, loading that into a hex editor is a bit ... well, overkill. The .hex file is a
text file containing hex strings.
You only need to know where to look ...
For example, in Soarer_at2usb_v1.12_atmega32u4.hex, it's here:
:100520000072000000380353006F00610072006524
:100530000072002700730020004B00650079006204
:10054000006F00610072006400200043006F006EC5
:1005500000760065007200740065007200000061A2At offset 0525, you can set the length of the string (including an UTF-16 0 at the end); that's followed by 03, indicating that it's a string. After that, 56 bytes come with little-endian UTF-16 characters. If you change anything, however, ...
- keep in mind that the last byte in the line is a checksum over the line (look up Intel Hex format for the calculation)
- I got no idea whether Soarer's command line tools will be able to find the USB device. Presumably, they will, as they're probably only searching for VID and PID.