thank you!
common ground between the arduino and the wrt54g's serial port was all i needed for a dirty 3.3v tx signal to be read from the arduino's rx.
i didn't do this before because both the wrt54g and the arduino are in the same 12v power supply although on different rails.
now instead of a constant stream of -1 i see other values when things are echod to the wrt54g's serial port... and it's even simpler than with the 2N3904.
thank you again!