well mister, TinyUmbrella doesnt work on 4.2
It does, but you have to be very careful. I have 4.2.1 with baseband 01.59.00 working on my iPhone4, and followed this procedure:
0) Start with an iPhone4 with baseband 01.59.00
1) Make sure you have SHSH keys for 4.1, 4.2.1, and if you want to untether, 4.2b3.
2) Set your /etc/hosts to either use Cydia or use TinyUmbrella's TSS server
3) Put your iPhone in DFU mode
4) use iTunes to RESTORE (option-restore) to factory 4.1
5) When this completes, you will have an error because the baseband update failed (you want this) ... Use TinyUmbrella to "Exit Restore". Phone will boot up.
6) Make sure /etc/hosts is still either pointed to Cydia or your TinyUmbrella TSS server
7) use iTunes to UPGRADE (not restore!) to factory 4.2.1 (just click upgrade, or option-upgrade if you have the IPSW already saved).
8) This will error out again because the baseband did not upgrade (again, you want this!), TinyUmbrella will be able to "Exit Recovery" as long as you used "Upgrade" and not "Restore"
8) Use Redsn0w 0.9.7b6 to Jailbreak your phone (tethered) (even if you plan to untether, you must do the tethered jailbreak first).
If you plan to continue tethered
9) Use Redsn0w to boot your phone tethered
If you plan to continue untethered
9) If you plan to use Skype, install Skype now, the JB Monte hack needs to be installed after Skype otherwise Skype will not work (you can reinstall the JB Monte later on if you install skype later).
10) Uncheck "Install Cydia" in Redsn0w.
11) Use Redsn0w to install the "Jailbreak Monte" which requires the 4.2b3 SHSH keys and IPSW. If you are not a registered developer, this will require piracy, so if you'd like to do this without pirating, you will need to sign up and pay to be an iPhone developer.
Good Luck!