How to jailbreak factory unlocked 4.2.1 on 3.10.01 ???

Hi .... first of all really sorry if this has been replied earlier because i tried to look for it in the forums but didnt quite get the answer... Anywayz does any one know that is it possible...?
I just got an iphone 4 from malaysia which was factory unlocked but is on 4.2.1 and with a baseband 3.10.01. Wanted to jailbreak it but didnt find an answer...
Any help would be really appreciated..
Thanx

Use greenpois0n RC6 to jailbreak.. iClarified - iPhone - How to Jailbreak Your iPhone 3GS, iPhone 4 Using Greenpois0n (Windows)

Did exactly as was told in the tutorial, but somehow i always end up at the message jailbreak failed... The green bar goes almost complete but just before the end this message appears "Jailbreak failed".... Any ideas, suggestions?
Thnx