Don't worry too much about having a PvP spec on a PvP server. You won't get ganked much by people your level. I levelled 4 chars over level 70 on PvP servers and never had too much trouble levelling. People usually stay away from rogues anyway ;)
I would advise you to just follow a normal levelling spec.
If you need help with those we used to have nice in-depth stickies that were great!