Has anyone worked with the dock connector outside the SDK frameworks? Say - is it possible to directly control certain pins?

I'm particularly interested in the serial port pins and I know that working with it has been documented before, but I'm trying to skip across all the subsystems and read/write from/to the Rx/Tx lines bit by bit. I'm not interested in any communication protocols.

I realize this is possible to a certain point but I don't know how far down the pipe can software go and where does the hardware take over. If that's the case at all, I don't know. I mean if there's part of a chip handling serial and you can only tell it to send whole characters, then I'm out of luck; but I don't even know that. So please, somebody, share your wisdom here.

Thank you!