All assuming you have 3.41 ps3.............
hmmmm right, i dont think you understand what needs to happen;
First you need a 2g/3g iphone a 4g/3gs wont work!
If you have one of the working ones you need to Jailbreak your iphone, google this 'iphone <your iOS here> jailbreak tutorial'
You will need to find your iphone iOS.
When you Jailbreak your iphone it will allow you to run unsigned code (e.g. the code to run the ps3 jailbreak) and it will most likely unlock your network aswell.
Once your iphone is jailbroken follow
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Kinda ironic you need a jailbroken iphone to jailbreak your ps3. Let me know how you get on.
P.S. you may be able to use an iphone 3gs, but as far as i know you can't.