From what I've been told, Mr. Parker disliked many of the applications and theories of FMA, mainly the ' cut to cut ' idea, as well as primarily striking on the downside of the circle.
To say that a weapon is simply an extension of the hand is a half-truth; a stick brings it's own rules, as does a knife. However, if the posture, angles, mechanics and positions are not correct ( ie, the body ), then all you have is random slashing, thrusting, and swinging.
To my knowledge, much of Mr. Parker's knife and club material was never publicly released ( GOD I'd love to read his unfinished works " Speak With A Club " and " Speak With A Knife " !!!!!! ).
So, to answer the original question, none. Mr. Parker didn't go outside Kenpo principles, concepts, and applications to implement stick or knife training; he didn't have to.
I'm not too sure how much influence FMA has had on Kenpo, I read somewhere the stick work of Kenpo is different from the FMA. Its best to either ask Mr Conatser or Dr. Chapel (both regulars on this forum).
I do know several prominent Kenpo instructors such as Mr Planas, Mr LeRoux and Mr Wedlake have/ do train in Kali/ Arnis/ Escrima. Most likely this has some influence on their Kenpo training.