When the 0000 comes up, you can use buttons 1,2,3,4 to change between digits (1 selects first digit etc) then keep pressing that same button to increase the number. For example, if your code started with 4, you would press 1 to select the first digit, then press 1 four times to change it to number 4 - then press 2 to move to the next digit and so on. After changing all the zeros to the correct number, you can hold down 6 for a few seconds and the radio should start working. This worked on my 51 plate clio, which also has the radio remote stick on the side of the steering wheel, but I found this method first. Presumably this method would also work for models without the remote stick.
Em, January 2011