Easiest way is to
1) 4948(config)# no
2) 4948(config)#
ie. after step 1 you will only be left with the 2nd boot statement in your running config. Then just add back in the first boot statement which should then appear as the 2nd boot statement in the running config.
Note this is fine to do while the switch is up and running, it will have no effect until switch is rebooted.
Jon