Is it possible to jailbreak and unlock an iphone 3g is now in 3.1.3?

I'm not 100% sure, but I think it might be possible. Suposidley there is no unlock for 3.1.3, however, what if I downgraded the firmware to 3.1.2 and then jailbreak and unlocked? I do not want to know how to jailbreak and unlock the "3.1.3", I just want to know if possible, in general, jailbreak and unlock, downgrade, or do whatever is necessary. I have an iphone 3g is blocked in the firmware 3.1.3 TELUS, and I get to 3.1.2, jailbreak and unlock so it can be used in Rogers. Please let me know if this is impossible, or what I recommend doing. I can use YouTube videos as my references for jailbreaking / unlocking. Thanks Adam

why on earth are called 'jailbreaking'? sounds so creepy and illegal.

How To: Jailbreak ANY 3.1.2 iPhone or iPod Touch Using Blackra1n | EASIEST WAY!