You do not edit them in exactly - they just are.
Playing as the French I upgraded my barracks in Paris to the second level and was able to recruit Buckeley's Irish regiment. You pay a bit extra than you do for a normal line regiment but hey, their stats are better a and they have the older looking XVIIIth century uniform; grey coat with no turnback, wide green cuffs and lapels.
They are off fighting the Savoyards and I am sure they will put a hurten on them.
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