Originally Posted by axmea?

Try this:
Use the transfer technique. Use small zip ties. Secure the zip tie to the spoiler's mounting hole using a small amount of masking tape where tab end lands at the center of the hole. Repeat this process to the holes you want to use to bolt the spoiler. 4 is enough. Set your spoiler on the hatch checking for eveness and if centered. Better to have help holding the spoiler down. Transfer the zip ties onto the hatch by firmly holding the tie and taping it onto the hatch. Lift your spoiler off slowly. Get a sharpie to mark where the tab lands and that's your drill mark for your spoiler holes. .