Note that if you have any class that gives access to Iajitsu Focus, then you use the class skill cap for maximum ranks, not the cross-class cap. So if the OA Samurai does get it, then you can enter Iajitsu Master after only six levels.

For another way to boost concentration checks, the Shape Soulmeld feat to get Vitality Belt would give you a +4 morale bonus to all Constitution checks and Constitution-based skills (all one of them). It's not an untyped bonus like Skill Focus, so it won't stack with any other morale bonuses, but morale bonuses are pretty rare unless you have a bard in the party, anyway.