You should be able to plug the sidecar into a MIDI interface and read the output with any DAW, if it’s just CC then it should be able to be reproduces by any other foot control.. Is there a Boomerang III MIDI implementation chart?
There is no MIDI implementation chart as MIDI control is not officially supported. I'll refer you to my previous message in this thread where I described the convoluted control scheme utilizing MIDI PC that I discovered.
Reading the output of the sidecar is the only way to go, but I no longer have one... do you?