From JohnZ's "Assembly Process" article at the CRG (link:
http://www.camaros.org/assemblyprocess.shtml)
"If the car required Z28, Z10, or Z11 stripes or a black rear end panel or rockers, they were masked and manually sprayed in the in-line repair booth/oven system after the reflow oven, including the cowl vent panel; spoilers were painted body color separate from the body, and were final-installed to the deck lid just prior to the repair booth."
and
"The cowl vent panel was hung in the side window opening on wire hooks all the way through the paint process."