PwnageTool 4.3 is already been released by iPhone Dev team for untetethered jailbreak on iOS 4.3.1 devices. This Pwnage Tool update can jailbreak all iDevices except iPad2 since iPad2 requires a bootrom or iBoot-level exploit to install and is not susceptible to either SHAtter bootrom exploits or limera1n. As of now, Apple TV 2G is only supported by Pwnage Tool 4.3.
You might be browsing through written guides for this jailbreak.
You can also check Video Guide of RedSn0w 0.9.6 RC9
Here, we are presenting a video guide made by blogsdna team for the jailbreaking. Since video is more helpful than written guides, so you will find it helpful.
Video of Untethered Jailbreak 4.3.1 with Pwnage Tool 4.3