Yup, as the other two have said. You need to remove the whole suspension, and chances are that you'll bugger some/all the ball joints while your doing it which will need replacing as well. Its not a quick or easy job. Im in the middle of making my own bush removal/insert tool.
Ive heard that when Polybushes go they just allow a complete collapse / fail? unlike the rubber bushes that can allow more flex before the point of no return? is this right or have I been misled?