for rx and tx you don't need to bypass anything as far as i can tell. as Mellis said, digital pin 0 and 1 are marked rx and tx. all data you send through the serial interface does flow through your usb-port to your computer and at the same time through the tx-pin. incoming data is read both from the usb port (coming from your computer) or the rx-pin on arduino.
this should be true as long as you don't assign any other function (digital in or out) to those pins.
as for RTS and CTS (ready-to-send/clear-to send) on your bluetooth module you can just connect them to each other i guess. those lines are used for flow control, i.e. to signalize that a device is ready to send or receive data. if you experience problems you might bypass/grab those line from somewhere on the board. maybe someone more familiar with the board will help you then.
see http://en.wikipedia.org/wiki/Serial_port >>>"flow control" for more info.
AND someone correct me if i'm wrong please!
please post your results here! i'm thinking of going bluetooth too.
k u k