Here is a simple guide by following which you can get untethered jailbreak on you Verizon iPhone 4 without needing Snowbreeze or restoring to custom iOS 4.2.8.
Step 1: Update your Verizon iPhone 4 to iOS 4.2.8 via iTunes. that can be downloaded here http://appldnld.apple.com/iPhone4/041-1022.20110503.5g8k7/iPhone3,3_4.2.8_8E401_Restore.ipsw or simply use itunes to update and restore to that firmware.
Step 2: Launch Redsnow (windows link) ( https://sites.google.com/a/iphone-dev.com/files/home/redsn0w_win_0.9.6rc18.zip?attredirects=0&d=1 ) and when it asks you to select the corresponding iPSW file, point it to iOS 4.2.6 instead of iOS 4.2.8.
For the mac version of redsn0w use this link : https://sites.google.com/a/iphone-dev.com/files/home/redsn0w_mac_0.9.6rc18.zip?attredirects=0&d=1> the rest of the procedure is the same just the version of redsn0w is different.
4.2.6 download link http://appldnld.apple.com/iPhone4/041-0177.20110131.Pyvrz/iPhone3,3_4.2.6_8E200_Restore.ipsw
Step 3: While selecting Install Cydia option, jailbreak your phone.
Step 4: Now boot tethered your iPhone using the Just boot tethered right now option from Redsnow.
Step 5: Launch Cydia and add the source http://djayb6.com.
Step 6: Using the search box in Cydia, search for CDMA iPhone Untether
Step 7: Install CDMA iPhone untether for iOS 4.2.8 package.
Step 8: Restart your untethered jailbroken iPhone 4 running on Verizon network.
Thanks to Djayb6 for developing this package and making iOS 4.2.8 unethered jailbreak possible.
I have followed this 6 times and get same results, black screen with flashing apple emblem. Why do you upgrade to 4.2.8 but point to the old 4.2.6 in redsn0w? I have completed this process pointing to both programs and get nowhere? Any help from past jailbreakers with the same issues would be great.