I am not 100% sure, more like 95% sure that you can get hit capped before ever stepping foot into a raid.
As a shadow priest, you only need 289 hit rating with Shadow Focus and Misery, that shouldn't be that hard to obtain. My shaman(who needed 342 hit to be capped) was able to get that mostly through some non-armor specific gear(trinket, cloak) and from enchants and gems.
A trinket in HVH gives 73 hit, cloak from Ebon Blade rep another 29, hand enchant 20 hit, icewalker-boots is 12 hit, accuracy 25 hit. Rigid Autumn's Glow gems are 16 hit, and if you are a JC you can get the rigid dragon's eye for 27 hit.
An since I know there is a hell of a lot more +hit cloth armor than there is +hit caster mail gear, yeah 95% sure hit can be capped before going into raids.
Edited, Feb 25th 2009 3:18pm by SynnTastic