If you wanted to get the old bushes out intact, you'd need a press.. but you don't - so you tear the rubber inner out with a prying tool and then hacksaw a slot through the metal outer (without cutting through the wishbone! ) and it just drops out with gentle persuasion..
New poly bushes, IIRC, then just drop straight in as two halves.
I tried the prying approach but nut surprisingly the rubber was damn hard, and without removing the wishbone fully from the car leverage was limited and it was a recipe for skinned knuckles. I took a cordless drill to it with something like a 6-7mm bit and just jiggled it about to muller as much of the rubber as I could get too, then used a hacksaw blade upside down in the frame (passed through the bush) make a cut in the shell before popping it free.
I think Turk used a blowtorch on the rubber - perhaps he has not got my oil leaks
New ones are indeed made of two poly halves and a steel centre bush that all slide together in a very satisfying way
using the all important magic grease supplied.
Steve