To coat your fresh tortilla chips with Dorito-goodness, you will first be spraying them with oil. Ideally, I would use my own oil and spray it on the chips with a spray bottle or
mister. However I don't have those things, so I checked out my grocery store's selection of Pam spray oils. If you're doing this, I suggest reading through some of the ingredients on the back before you buy - a lot of those products have strange ingredients for non-stick purposes, that don't really apply here.
When you're armed with oil, spray your chips lightly while they're still on the baking sheet. Dump into a large gallon-sized Ziplock bag, and add powder (again, about 2 teaspoons per baking sheet of chips. If you like them stronger, add more!)
Shake! You'll see that the powder easily sticks to the chips.