I think the special tool they mention screws into the injector pump body . you can do without it but it is a bit trial and error . the tool is just a threaded rod with a turned down end . you can make one if you have access to a lathe ,or you can drill through a bolt ( with the right thread to fit the timing hole ) and use the drill as a dowel . Failing this you can just use a drill as a dowel but you have to try to centre it in the hole as best you can . Of course all this is 1" down a 3/8" blind hole . only turn the engine in its running direction , if you go past the mark , go round again . let us know how you get on .....Al