I see a lot of people saying they are using Beam Overload Three. I've got Beam Overload Two but can't find Three.
Mayby I'm not speced for it or something but where can I find it?
you would have to find BO on the exchange that has the skill, If you find one that goes for Cheap
you then commission that BO or train one of your BO with that skill that BO would then Disappear from you uncommissioned BO list.
Pretty much, any level III ability cannot be bought from any BO trainer, you have to find a rare BO that has it.
I'm guessing that it cannot be trained by a Tactical player Captain, since it does mention that it can in STOWiki. (And there doesn't appear to be a corresponding skill to grant the Captain the ability to train it)