AD Kennen can work pretty well due to his hard CC, good ADC stats, and dash. The main problems are the fact that he can't jump over a wall without Flash and the fact that only his W's passive scales with AD.
Here's what I run. - AD Marks and Quints, Armor Seals, Scaling MR Glyphs (no need for Armor Pen when you W does magic damage). - What should be standard masteries for an ADC (21/9/0 taking the the entire left side of the offense tree minus Summoner's Wrath) - SS's: Barrier or Cleanse/Flash (Barrier works well with his E while Cleanse is for CC. You can go with Ignite if you want more kills and take Summoner's Wrath with it)
Start Boots+3pots/Doran's Blade/Longsword+2pots. Rush BT and get Berserker's if you think you need more movespeed. Then I get Statikk Shiv for more magic damage and because Kennen has terrible waveclear outside of dashing through the minions and using his W, which can get him caught out and killed. Then I either get IE and then start building a defensive item or two or I get the defensive item first. You can get GA, QSS, or Warmog's on him. You could also get Banshee's Veil, but the mana is wasted on him. Your last offensive item should be Phantom Dancer and I've never actually gotten to the point of selling my boots for Zephyr.
You can also use Runaan's Hurricane as your first ATS item. It makes it so Kennen's W will stack even faster. I'm not too familiar with Hurricane builds, but I don't think they build any crit at all so you wouldn't be getting IE. BotRK or another BT would probably be better.
tl;dr: Can't make it much shorter than that. --- Generation 30: The first time you see this, copy it into your own signature (on any forum) and add one to the generation number. Social experiment.