You don't use 4.3.5 ipsw you use 4.3.4 its tethered on Redsn0w I just I mean just finished jailbreaking my iphone 3gs
If you don't know how to do tethered you load up redsn0w browse for 4.3.4 ipsw and it should process it
hit next install cydia,
next do the DFU mode shit
then it should say finished on redsn0w and
then it'll go to a thing downloading and have a pic of a HDD
then it will load the running pineapple my favorite part,
your ipod will look normal then you go back to redsn0w and do it again but in the options hit tethered thingy and it will have a small pic of running pineapple then it will load up and you will have cydia go to it hit one of three options
I bought my iphone last week its my first time jailbreaking but if not google
"How to jailbreak _insert idevice name here_ 4.3.5"
I hope I helped on what little bit I know