Funny you should ask. I gave my primary school kids this one as an end of term treat. It'll take you all of 10 seconds to learn the head. After a week of listening to dozens of kids get the notes and not the feel of this tune, my advice to you would be the same as I give to the kids.
1. Articulate!!! Don't just slur your way through the line. Funk is all about articulation.
2. Unless you're playing a pea shooter mouthpiece, push your sound a little. More often than not, funk is a brighter sound and no one wants to hear French Horns playing this tune. So overdrive your sound a little.
3. Listen to the recording and play along with it until you start to feel the time rather than count the time. Getting a tight horn section is what separates the great funk bands from the herd.
Best of luck and have fun. It's not a hard tune and the audience always likes this one.