I suggest first picking up the steath improvement talents that passively increase your stealth and detection of stealth.
Camouflage
Master of Deception
Heightened Senses
I recommend focusing on these talents for a few reasons. Firstly, Subtlety (which is what you said you wanted to focus on) relies heavier on Stealth than the other two trees will. Not saying that the others dont depend on stealth in a PVP setting, just that subt. is huge on burst dmg and w/o heightened stealth and stealth detection you'll be spending more time out of stealth then you'll want to be. That being said, i would recommend a build similar to this. Now, what was said by posters before me is true for pvp...there is nothing set in stone. I would recommend picking up any talent your gut feels you need. You'll have plenty of time to play around with the differing talents and should be able to find which fit your playstyle. Rogues are extremely versatile and there are plenty of successful talent builds for you to experiment with.
I hope this helps a bit...scraped it together while at work so ask if you need anything elaborated on.