Hey Dave, welcome!
I don't think it is possible to walk in from Biscuit city, you can head up stream in a boat from there.
The only good way to walk in that I know is from the main Great Swamp entrance, but it is quite a hike if I am not mistaken. Plus I think you need to get a special permit to hunt the impoundment, it is free at the swamp office. There a a few ground rules to hunt there as well.