Switching git hosting solutions should be just a matter of changing the git URL.
AFAICT this can be achieved by turning off the issue tracker and wiki on GitHub repos. This would mean we use the mailing list, Chicken's issue tracker, or email/irc for coordination. Since it's just a few tools, maybe not worth overthinking this?
Another option would be to put all the tools in one git repo on code.call-cc.org, and give write access to that repo to the few people who need it. Is there some way to have it send email notifications, similar to the GitHub "watch this repo" feature?
