Currently on a 3Gs with 4.1(8B117) Unlocked with UltraSnow at BB 05.12.01.
I am planning on using snowbreeze to upgrade to 4.3.3 and keep my unlock, but based on the instructions, it seems that i have to update the phone to 4.3.3 first, which would update the bb and cause me to lose my unlock.
I do NOT want to do the ipad hack if i can avoid it..
The instructions are probably telling you to update to 4.3.3 with a custom firmware. Using a custom firmware, you would create it with Sn0wbreeze and simply do a shift+restore in itunes, browse to the custom fw and let it do the upgrade/restore. It's upgrading and jailbreaking your phone in one step.