The PvP Access Kit is a purchase from the Guild Wars In-Game Store that allows access in PvP to the Professions and Skills from each of the three campaigns.
The kit unlocks 40 skills (20 elite, 20 normal) and 20 item unlocks for use on any PvP only character on your account.
The kit costs 19.95 USD / 17.99 EUR / 11.99 GBP from the in-game store.