Im not sure how you would go about hosting it yourself on installer, but you could ask MMI to host it, its free and we wouldnt have to add a separate source since MMI is a community source. If you are only going to create a few themes, and want them to be available to the most amount of people, I would suggest going there.
EDIT: Also, you could try going to
http://www.customizeapp.com/ and upload your theme there because a lot of people use Customize 2.0 now instead of summerboard. A plus about putting it on that site is that you can also add custom application images (such as chat bubbles, calculator skin, etc.) system images (such as carrier image, battery image, status bar background, etc.) and other things.