As far as I know, you just need to go get a permit to keep snakes over six feet (or at least that's the way I interpt it).

I do live in IL Shelby, but I haven't looked into getting a permit or anything, since I don't own anything that should top six feet. When I get ready to get a larger snake or one that is far more likely to top six feet (like a BCI, for example) I will look into getting a permit.

Maybe try emailing somebody at the Chicago Herpological Society, if you're not a member. Somebody within that group ought to know