I have requested my webhosting company to set up Mercurial to ensure that after i SSH into my web site to make changes, I'm able to submit the files straight to version control at Google code.

The support guy is asking me for "all of the particulars" including which ports it uses to allow them to find out if they fit using their security policy.

How do you discover what ports it uses, and what else might they have to know?

You don't have to operate a server whatsoever for Mercurial. Your sysadmin just must make certain you've ssh use of the equipment which the Mercurial executable 'hg' is within your user's path. When they will not help on that last part you could do-it-yourself putting hg in your path. The Web addresses that you'll push may be like:

  ssh://yourusername@thesystem/path/in/your/homedir