You will need a letter from your Congressman, IF you want to go WITHOUT an appt.

However, you can get an appt thru the 800 line within that time frame. The best place to go is the DC office--it's a short metro ride and CVG nonrev is easiest with first am flight--last one iback s 5 something. The lines must be down to manageable length by now!! Most of waited 2-3 hours just to get in W/Letter. Then you wait some more. Pickups start around 3:30.
There is an excellent little Italian restaurant down the block (luigi's maybe?)--glassed entry--$10 lunch will make it worth the trip!!

I just did this a few months ago to get my extra pages required for a visa. Be aware that you will pay the $65 expedite fee ON TOP of the usual passport costs.

Also, recommend you get roundtrip fare paid in advance--I barely made the train and flight beacuase of some screw-ups by my Congressional office workers (who knew??). The metro station is only a few blocks from the passport office.

Hope that works!