Here is a proposition for playing Kennen as a AS/AP hybrid, created with Mc8Lovin's initial idea in mind.
The main point is, with high AS you can stun more often, as Kennen's every fifth attack stuns. This build goes extremely well with red buff. You won't have a high damage output, but with your stun you can be the deciding factor in 5vs5 team fights thus helping to win the game.

Please feel free to comment!

Pro:
- A lot of stun, helps in team fghts
- Good farming
- Good splitpushing
- More Ninja feel than AP Kennen

Con:
- Squishy
- Hard to play; get into enemy team, stun all, and get out before you get killed
- Mediocre damage output

W's passive gives you high damage with every 5th attack, so you should max it first.
Q is your skill shot with nice damage, so max it out second.
E is for stunning and escaping, so you should learn it early and max it out last.

9 / 0 / 21 underlines the summoner spell choice and gives CDR, movement speed.

In summary, this is a build for team players, not for the ones that only want good stats.
You can take a solo lane, but be cautious if you're against 2 enemy laners or Cho'Gath, Caitlyn, Lux. If there is no jungler in your team, you could be the first choice to run through the jungle and farm the creeps mid-game with your high attack and movement speed.