Hello Arwyn, Just to let you know the only way to do the job is to strip it down and as luck has it I can obtain the torx high tensile screw bolts from a local engineers merchant as they stock all diameters and lengths both pan head and countersunk.
If anyone replacing the water pump on the M16 engine use locking fluid on the bolts holding the plate. Plus always use wet and dry 220 grade paper cut to the back side of the adjustable timing belt roller to prevent this slipping. This information normally comes with the new timing belt along with the wet and dry disc. I have all the instructions if anyone needs them if buying a unboxed belt.