Hi there. In January of this year, Hotroddave sent me a picture and discription of how he did his. He sent me a picture of the tool he made, but to save my sole I can't find it now. He used 2 welding clamps to hold it in position while he drilled the holes. You could send him a quick note and ask that he post it again. I did a search for his name and previous posts, but didn't come up with the right one. If I recall correctly, it was under $20 for materials if you had to buy them all outright to make the "jig."
Hope this helps.