By Default the ports will be sewt to Auto-Negotiaiton. If you want to hardcode a 1000Base-T/SX switch port on 5400zl series switch, use the following...
int <port_number> speed-duplex 1000-full
you are more likely ging to need to do this on a Fibre port which is conected to other vendor equiopment, I cam across this when connecting to some old legacy Nortel kit who's SX port was hardcoded to 1000FD.
HTH