Hi!
It's really tricky. You need to unfasten the engine support on the left of the engine compartment, jack up the engine, block the camshafts on the right side, above gear box and the drive shaft with specially designed tools... So, if you don't have the necessary tools, forget it! Take it to a mechanic. It's well advised to change the water pump at the same time and the belt tensioner together with the accesssory belt since there is a possibility that it breaks ( if old ) and gets into the timing belt and destroys the engine again!
Good luck!
Michel Malavialle
July 2005