I got the following addition on my Dell XPS LED code from David Pritchard.

The new version of the code has a “-touchpad” argument. Specify “-touchpad 1” to turn the XPS 2 touchpad light on, “-touchpad 0” to turn it off.

Here is the updated source code and executable. The executable should work without Cygwin now. (Note to self: Use “-mno-cygwin” gcc option to strip out the dependency)