A small amount of progress. I can connect to the camera quite easily by changing lines 819 & 821 of gphoto_ccd.cpp to
gphotodrv = gphoto_open(camera, loader.context, "Canon EOS M10", "ptpip:192.168.68.79", shutter_release_port);
The problem is now that it won't capture photos - or do anything really. But the camera thinks it's connected, and if I shut down indiserver then the camera reports that a disconnection has happened.