If you've got Linux (or Windows 10 with 'Linux on Windows' installed) then it should be pretty straightforward to rebuild - or @JumJum's firmware builder should work too
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Ok, just changing the variables value will be enough: https://github.com/espruino/Espruino/blob/master/boards/PIXLJS.py#L25
If you've got Linux (or Windows 10 with 'Linux on Windows' installed) then it should be pretty straightforward to rebuild - or @JumJum's firmware builder should work too