Well scan it they do. For passengers incoming into B and C, their Ready to Fly entry needs to be prepared and that comes with scanning. Ironically I don't think the scanning is the problem, I am not sure there's any logic there. But there are 2 staff members you need to get past first, at the front of B and C Flight Connections, one of whom stands by a big display screen of flights. If your flight isn't listed, you're not getting through. You can use B to access C, however. So to answer your question, you can't do this unless B and C are showing as your next departure. The B and C updates show up typically 60 to 90 minutes before departure.

If you are on an A380 you're almost certainly going to be going from C, so I guess you could hang around for a bit until the gate is declared. I've done that.