A while ago, the nice people at ModMyiFone put together their own installer source. This source usually has up-to-date hacks in installable forms shortly after they become public. I've been besieged by kind commenters reminding me to put up a general post to let everyone know about this. If you'd like to add the MMI source to Installer, here's how.
In Installer.app, select Sources then tap Edit (top-right corner) and then Add (top-left corner), type in http://modmyifone.com/installer.xml. Tap OK, wait, and then tap Done. MMI gets added as a listed but "untrusted" source. Oh well, you can't have everything.