If there's a rideable route, you can find it with this website:
www.viamichelin.com . Use the cycling option. I'm not saying that this is a good idea, just that viamichelin can find you a cyclable route. From what I remember (it was a long time ago), central Paris isn't a bad place to ride a bike, but CDG didn't look too bike friendly.
Google Earth would be a good way to check out your route ahead of time.