The script itself does not need any installation other than making it executable on Linux:
$ chmod a+x isrcsubmit.py
However, the libraries should get installed so that the script has access to them.
On Windows and Mac OS X it is recommended to download the binary packages of isrcsubmit. These include all dependencies.
Some Linux Distributions already included isrcsubmit in the repositories. If not you should at least find the dependencies with the software management tool of your distribution. If you can’t find these packages you can try using isrcsubmit 1, which only depends on python-musicbrainz2 and libdiscid.