Take the Creekside Gondola to midstation, change to the Red Express quad chair and turn left as you get off the top of the Red Express chair and ski/board to the lightboard. Look for the rainbow flag.
From ON Blackcomb Mountain
Assuming you started off on Blackcomb early in the morning you can use the new Peak2Peak Gondola from Rendezvous Lodge so you can make your way across to Whistler mountain. On arrival at Whistler mountain exiting that gondola just walk across to the light board just a few hundred feet ahead!! Look out for the rainbow flag.