It's true, there is a White-winged Scoter (hanging with a Surf Scoter) in Cape May. The call came in the late yesterday afternoon from CMBO volunteer Chris Hajduk and Bob Fogg was the first to confirm the sighting. In looking at the eBird Rare Bird Google Gadget (just at the top of the page you are reading), I see that Tom Magarian (NJAS research associate) has seen the bird today as well.
Assuming that Tom had the bird in the same area, you'll need to walk down Poverty Beach (the beach at the north east end of Cape Island) till you get to the US Coast Guard property line. Scope from that area toward the pilings and look for two dark sea ducks floating in the water (pretty much the only birds on the water there yesterday.) The birds were diving quite a bit yesterday but luckily the current (an their legs I assume) carried them quite close to our location. Also, while you are heading out take note of the little fluff ball Least Tern chicks wandering around the roped off nesting area on the beach. I did not count but there must have been close 10 or 15 that we saw.
For a photo of the birds from yesterday visit Bob Fogg's web site, where he has posted a photo which should help you to get an idea of what you are looking for.