Crumb, look at the one Marty put up.......basically the same, only long enough to be pressed all the way thru the hub.........like 2-1/2", or whatever is needed..............
You're just reducing the diameter of the hole the axle will fit into.......
May have to set it on something like a towel or cardboard & lay a small piece of wood against the bushing to tap it into the wheel without banging it up on the end......others who've done it can inform, as I've just done it with other types of machinery parts, not kettle wheels...........