Thanks for the advice to install HX Edit. The installer apparently also installs the USB driver required by hx stomp.
My original issue was, that when plugging-in the hx stomp to my laptop USB (it uses USB 2.0), the Windows device manager displayed a yellow triangle and an error message indicating that the USB device (ie hx stomp) is not operable. Therefore I couldn't use it in Ableton.
Finally, HX Edit is anyway a much better tool for editing presets than the interface on the hx stomp.