To enable Halo 3 Sunrise, set & save it as a plugin in dashlaunch. Reboot your console and you should be all set. If this doesn't work, you may need to enable sockpatch & disable xhttp in dashlaunch (settings under the Network tab).

Note: If you have XCommunity enabled, you can ignore the steps above as Sunrise is included with XCommunity.

Friendly reminder that cheating is not allowed on Sunrise. If you do this, your console will be permanently banned from the server.