3gs 3.1.3 upgrade to 4.0.1

[hepsmalls]

I've got a jailbroke (via jailbreakme 3gs 3.1.3) that I need to move to iOS4 because of new wifi network settings on my campus. I've got SHSH iOS4.0, 4.01, 4.0.2 showing on Cydia. What's the best way to upgrade and keep the phone jailbroke? Mac 10.64, iTunes 9.2.1 if it matters.
Thanks!

[iYeow]

I don't know how to edit the hosts file on the mac but on a pc this is what you do :
Run Notepad as Admin , open up hosts file and add this line :
74.208.10.249 gs.apple.com
save it and reboots your pc
Now do the Shift + Restore to 4.0.1

Itunes 9.2 to 10 is good.