The trick to it is to lightly clamp the belt onto one of the pulleys, i used a pair of mole grips very lightly just to hold belt on then worked from left pulley across top to the right then down to bottom right pulley and across to lower left pulley, it did take me a good half dozen times, as i always ended up a tooth out, which of course would throw the timing out.

One more thing to look out for is the front crank oil seal, if you have any signs of weeping oil then change it, i did mine, its easy to do.