There’s some great news for developers on iOS 6 beta 4. You can now jailbreak the latest Apple beta using the RedSn0w tool. As always this is a tethered jailbreak but will allow developers to ensure Cydia tweak/app compatibility for iOS 6…
MuscleNerd from the iPhone Dev Team confirmed the compatibility of RedSn0w with the latest beta. The current version of RedSn0w (0.9.13 dev 3) on Mac / Windows will jailbreak iOS 6 beta 4. Just point RedSn0w at the iOS 6 beta 3 IPSW file and you’re good to go.
Remember kids, this will NOT install Cydia. This is also only compatible with A4 devices. But if you’re a developer trying to ensure jailbreak tweak compatibility with iOS 6, this could be a saving grace.
Source: MuscleNerd