I tried to figure out how to compile and run jsl. As I just needed the binary, here is how I finally got it working in a pretty nice way:
Extract all files in that folder and go right into the src folder.
$ make -f Makefile.ref
If all dependencies are there, you'll have a folder LinuxALLDBG.OBJ created. Go right into that and there is a file called "jsl". Copy that file to your bin folder (~/bin, /usr/local/bin, /usr/bin, /usr/sbin ... wherever you appriciate).
Now you are capable of running:
$ jsl -process file.js
whereever you want!