The iPhone Dev Team have now released the redsn0w 0.9.6 rc7 version to bypass some screens that come during the iOS 4.2.1 tethered jailbreak with redsn0w where “Just boot tethered for now” option is used. The screens could bypassed using some commands. Below is the official description from Dev Team’s blog :
We’ve updated redsn0w to include “one-click” support for those of you running the tethered 4.2.1 jailbreak. Using command-line arguments, you can now bypass the screens you’d normally see as you use redsn0w to “Just boot tethered for now”.
Download Redsn0w 0.9.6 rc7 for Windows from here
Download Redsn0w 0.9.6 rc7 for Mac OS X from here