As per the rules for transport vehicles, embarked units cannot be targeted or affect in any way while embarked on a transport.
actually the rule is cannot
normally do anything or be affected in any way.
So you'd have to check the entry for the specific psychic power, the specific unit you want to benefit from it, and the specific vehicle they are in to check for exceptions.
The Open Top Rules for Raiders state that any restrictions or modifiers that apply to the Raider also apply to the passengers (when shooting).
So if you could fine a psychic power that gave you a modifier to your shooting attack roll, that would work. Ancestor's grace gives you a reroll and not a modifier though, so that wouldn't.