You need a press or vice, and an assortment of sockets, and metal tubes. Various bits of wood and metal come in handy too, and some WD40. Basically you have to push the old bush housings out using enourmous force, while ensuring that you dont bend the arm. A few careful cuts with a Dremel cutting wheel also helps to get the old stuff free. Use the grease supplied to lubricate all the surfaces and to help in pushing the polybush into it's housing.

While you are there, it would be a good time to remove the crappy rear brake valves in favour of adjustable bias valves - or even new lines and a front/rear split.