Steps to unlock a factory 3.1.2 3GS with old bottom? (never unlocked)

[AlvinNguyen]

I am trying not to mess this one up so I'm planning on this route. Any advice or input appreciated!

Jailbreak 3.1.2 with Spirit
Unlock with ultrasn0w
Save SHSH on Cydia
Patch spirit jailbreak with Spirit2pwn
Upgrade to jailbreak on custom 4.0 firmware from pwnage tool 4.0
Unlock 4.0 with ultrasn0w

 

[Applejuiced]

No spirit.
Use blackrain. Then update to custom 4.0 created with pwnage.
Then install ultrasnow to unlock.