Kolsch is often used as a jumping off point for flavor experimentation (mistakenly so, in my opinion...I'm firmly in the same camp as Nosybear on this). A true Kolsch should drink like a fine lager, clean, malty simple.
That being said, an extract brew may not exactly hit all the style points, anyway, so a little "personalizing" might be fun. The honey, as mentioned, may not be very impressive, though I've done precisely what you're thinking quite a few years back and to the best of my recollection, experienced a little honey flavor. Definitely a lighter, thinner beer than it might normally be, though.
Best way to do it is use a new, sealed container and pour it directly into the fermenter after a couple of days of activity. That'll keep some of the volatile flavor molecules in place rather than blowing everything out during high krausen. Definitely double down on the flavor by steeping some honey malt. And use a mild, floral hop like Tettenang.
I find wheat beers to be better vehicles for added flavors. Mango Witbier, Apricot Hefe, Strawberry/basil American Wheat...things like that can be really nice if not overdone.
Good luck with it.