Sneaking extra birds onto the plane

We're moving from California to Massachusetts with our four birds
(Bourke's parakeet, lovebird, green-cheeked conure, African gray). The
problem is that the airline (U.S. Airways) only allows two pets per
flight.

We have reservations to bring two birds as carry-ons. The plan was to
have two friends fly on a different flight with the other two birds.
However, we just found out that they may not be able to after all.

I'm thinking about putting the three small birds in one carrier
(partitioned to keep the bourkie away from the other two) and sneaking
them on as one pet. Has anyone done this?

Can someone who has flown with birds recently please tell me what to
expect? How are the birds and carriers inspected by TSA? (Do they
just look? Metal detector wand? X-ray? Do we take the birds out---
what if they're flighted?) What does the airline do at check-in, the
gate, and when we board?

Thanks,
Vebjorn