tFunk:
It sounds to me like you are looking for a coaster-break set up, not a fixed-gear.....
i want to be able to brake by backpedaling just like the old days on my 20" wheeler and make skid marks!
A fixed-gear drive train will not allow you to coast at all, and if you pedal backwards, the wheel turns backwards. There is no breaking mechanism -- your legs to the braking.
A coaster brake system (like on my old 20" bike) will allow you to coast, and if you start to pedal backwards a brake in the hub engages, often locking the rear wheel for cool skids......
If you are indeed looking for a coaster brake rig, you will need a new hub.