How to update 3GS on 4.1 JB with BB 06.15 to 5.01

[senorFunkyPants]

Pretty much as subject:
I have an iPhone 3GS on jailbroken on 4.1 with BB 06.15 that I want to update to 5.01. I'm not bothered whether its jailbroken or not and I don't need to unlock as I've now got it factory unlocked.
I've searched and I can't find what I need to do.
Can anyone spare a minute to point me in the right direction?
Ta.

 

[Applejuiced]

Factory unlocked or not ever since you installed the ipad bb you can only restore and update to custom ipsw's.
Use either redsnow or pwnage to create a custom 5.0.1 and then put your iphone in pwned DFU mode and restore to that ipsw using itunes.
Follow this step by step below.
http://www.iclarified.com/entry/index.php?enid=18932
Go up to step 15 when you select your no_bb custom ipsw with itunes and then you're done.
This will put you up to 5.0.1, non JB firmware. If you want to JB it also follow the rest of the tutorial.
Good luck.

 

[senorFunkyPants]

Thanks..I've downloaded redsn0w 0.9.10b3 and created a custom 5.01 ipsw.
So IIUC I can go straight from 4.1 to 5.01 with this custom ipsw?
Edit:
Worked great...thanks for taking the time to answer.