Precautious question: Need to update from 3.1.2 to 3.1.3 (BL 05.11.07)

Hey guys,

blackra1n failed on me after half a year of working great, so i guess its update time.

My phone is a week 49(?) 3Gs with 05.11.07.
I got a 3.1.3 SHSH file saved on my MAC (no clue what to do with it though).

If i am not mistaken, my only chance to re-obtain a working device is to update to 3.1.3 and then use the new ultrasn0w to unlock.
(tried all the hints in the sticky thread for blackra1n.)

What is my best option to do the update?
Thought of pwnage... is that correct?


Thanks for any help!!

dP

I have the same question. My phone is on week 41 (new bootrom) 3.1.2 os used blackra1n to jb and unlock. 3.1.3 shsh is saved. What is a good way for me to upgrade to 3.1.3 so I can get rip of the tether unlock.