Dear moderators i dont know what the proper procedure for posting a help guide is, so hopefully im not infringing on any rules. Hope this helps:

i had my iphone locked on the 4.0.2. update (01.59.0 baseband)
i had stored my 4.0.2. shsh on tinyumbrella

i used part of Trunkz limera1n tutorial http://www.hackint0sh.org/f137/175071.htm

Step 1 - Preserving your baseband (only works on iPhone 4)
If you do not need to preserve your baseband, then skip this step completely. At the time of this guide, I'm running iOS 4.0.1 on an iphone 4, and want to preserve my baseband, as upgrading to iOS 4.1 will normally upgrade the baseband to an unexploitable version. For the iPhone 4 only, it is possible to remedy this;
Ensure that you have your SHSH blob saved by Cydia or TinyUmbrella. For the purpose of this guide, I will assume that cydia has your SHSH blobs.
Download and run the most recent version of TinyUmbrella from The Firmware Umbrella - it will ask for permission to run.
Click Start TSS Server
Click Stop TSS Server
Close TinyUmbrella
Goto C:\Windows\system32\drivers\etc & locate your hosts file.
Open the hosts file with Wordpad, and check that the following line was added by TinyUmbrella:
Quote:
74.208.10.249 gs.apple.com
Note that this line must not have a # symbol at the beginning of the line. If the line is missing or has the # symbol, repeat the tiny umbrella steps above. (or add the line manually - editing this file requires administrative rights - be sure to launch wordpad as administrator)
Step 2 - Restoring to iOS 4.1
Ensure your iPhone is plugged into your computer, and you are running iTunes 10.
Start up iTunes.
Navigate to the iPhone page, and press the Restore button, and follow the prompts to restore your iPhone to iOS 4.1
iTunes will now begin to download the iOS 4.1 restore file, which weighs at approx. 590MB, so this may take a while depending on your connection.
Once that has finished, with any luck iTunes will begin to restore your iPhone to iOS 4.1. Relax, and let it do its magic.
Your iPhone will restart as soon as the restore has been completed, and two things will happen:

If you had followed step 1 and preserved your baseband, iTunes will give you an error (error 1004 normally). Dont panic! This error is good. It means that iTunes did not update the baseband, which is exactly what we want. Now download TinyUmbrella if you havent already, and run it. Now at this point, select the 'Kick device out of recovery' button, and it should kick the iPhone out of DFU mode, and back to its homescreen.
If you skipped step 1 (i.e. you did not preserve your baseband), then you will be greeted with the activation screen.

Since limera1n will activate your iPhone for you, you do not need to use iTunes to activate it, and thus wont require the use of an official sim card in order to so.
iTunes may (also) at this point, ask you if you would like to restore your iPhone to an earlier backup (if you had done one), you can do this now, or do it later. I would suggest later, as you can sync any apps after you have jailbroken & installed cydia, to minimize any issues popping up.

Step 3 - Jailbreaking
i decided to with greenpois0n for the jailbreak, so i went to their website greenp0ison.com and downloaded their software, i followed their instructions and i opened my iphone oppened the app call loader installed cydia, updated cydia, installed ultrasn0w and rebooted.

thats it!

Originally Posted by petercheca

Dear moderators i dont know what the proper procedure for posting a help guide is, so hopefully im not infringing on any rules. Hope this helps:

i had my iphone locked on the 4.0.2. update (01.59.0 baseband)
i had stored my 4.0.2. shsh on tinyumbrella

i used part of Trunkz limera1n tutorial http://www.hackint0sh.org/f137/175071.htm

Step 1 - Preserving your baseband (only works on iPhone 4)
If you do not need to preserve your baseband, then skip this step completely. At the time of this guide, I'm running iOS 4.0.1 on an iphone 4, and want to preserve my baseband, as upgrading to iOS 4.1 will normally upgrade the baseband to an unexploitable version. For the iPhone 4 only, it is possible to remedy this;
Ensure that you have your SHSH blob saved by Cydia or TinyUmbrella. For the purpose of this guide, I will assume that cydia has your SHSH blobs.
Download and run the most recent version of TinyUmbrella from The Firmware Umbrella - it will ask for permission to run.
Click Start TSS Server
Click Stop TSS Server
Close TinyUmbrella
Goto C:\Windows\system32\drivers\etc & locate your hosts file.
Open the hosts file with Wordpad, and check that the following line was added by TinyUmbrella:
Quote:
74.208.10.249 gs.apple.com
Note that this line must not have a # symbol at the beginning of the line. If the line is missing or has the # symbol, repeat the tiny umbrella steps above. (or add the line manually - editing this file requires administrative rights - be sure to launch wordpad as administrator)
Step 2 - Restoring to iOS 4.1
Ensure your iPhone is plugged into your computer, and you are running iTunes 10.
Start up iTunes.
Navigate to the iPhone page, and press the Restore button, and follow the prompts to restore your iPhone to iOS 4.1
iTunes will now begin to download the iOS 4.1 restore file, which weighs at approx. 590MB, so this may take a while depending on your connection.
Once that has finished, with any luck iTunes will begin to restore your iPhone to iOS 4.1. Relax, and let it do its magic.
Your iPhone will restart as soon as the restore has been completed, and two things will happen:

If you had followed step 1 and preserved your baseband, iTunes will give you an error (error 1004 normally). Dont panic! This error is good. It means that iTunes did not update the baseband, which is exactly what we want. Now download TinyUmbrella if you havent already, and run it. Now at this point, select the 'Kick device out of recovery' button, and it should kick the iPhone out of DFU mode, and back to its homescreen.
If you skipped step 1 (i.e. you did not preserve your baseband), then you will be greeted with the activation screen.

Since limera1n will activate your iPhone for you, you do not need to use iTunes to activate it, and thus wont require the use of an official sim card in order to so.
iTunes may (also) at this point, ask you if you would like to restore your iPhone to an earlier backup (if you had done one), you can do this now, or do it later. I would suggest later, as you can sync any apps after you have jailbroken & installed cydia, to minimize any issues popping up.

Step 3 - Jailbreaking
i decided to with greenpois0n for the jailbreak, so i went to their website greenp0ison.com and downloaded their software, i followed their instructions and i opened my iphone oppened the app call loader installed cydia, updated cydia, installed ultrasn0w and rebooted.

thats it!

So... basically you used Trunkz guide but jailbroke with greenpois0n instead. I'm not sure this warrants a new guide.