Hi Vince, I am new to all this, on Mach3 anyway, and I have Ver 3.042.
On the Please Choose Operation screen it is in the centre row and listed as Multiple Hole Pattern, second in from the righthand side.
Once you click on that you are taken to the Tool Properties screen and then Continue on to Drill Hole Positions.
I probably could have made that a bit clearer originally but I was just on that page when I posted the response to your query.
Ross