You should have no alacrity at all as a tank. Alacrity is a damage-boosting stat, nothing more, and since it competes with shield, you couldn't possibly take any of it without significantly gimping your mitigation. So, no.
Accuracy is more interesting. To answer everyone's question: tank proc effects are on ability *activation*, not on hit. Thus, *activating* Slow Time or Project gives a stack of HS (even when they miss). *Activating* Riposte triggers Blade Barricade. *Activating* Energy Blast grants 25% absorb and consumes your stacks. Fundamental tank procs are immune to interaction with accuracy. With that said, accuracy can still have an effect. For example, if my Project misses, I keep the Particle Acceleration proc. Hilariously, if my Shadow Strike misses, I keep the Shadow Wrap proc and get to use SS a *second* time (back to back) with the same reduced cost.
Since fundamental tank procs do not have a negative interaction with survivability, accuracy itself has no survivability contribution and thus should be considered a damage stat that competes with shield. Thus, it is in the same category as alacrity. (do not want!)
Thanks. I assumed so, I just wish they didn't throw it on the tank gear. /sigh BW...