I don\'t have a local code copy/etc, I just want to download a single specific git commit so I can view it. I have the url for the git repository:
git://git.kernel.o
This would appear to be impossible. According to a discussion on kernel.org, the protocol will only allow named refs to be fetched. If you don't wish to download the snapshot from the git website, you'll have to clone the entire repo.
(You may wish to read the manuals for git-fetch and git-ls-remote.)