The tool isn?t for locking the cams it?s for checking that the timing is correct, they do the locking pin which stops the crank and a tensioner for correctly tensioning the timing chain whilst doing the above. The timing jig could be used to lock the cams in place but you could use cable ties etc, just make sure you have the timing marks aligned before doing what you?re going to do and everything will be ok.
the timing marks on the cams are both at 9 & 3 so what to do is when you get the timing marks aligned on the crank timing gear then mark both lines on the cam gear that face each other. If you do this then you can?t go wrong.