Quite easy, just make sure the switch on step 1 is also 4507 or something similar IFS:
1. Switch# copy bootflash: slotx:
( replace x with pc flash slot 0 or 1 )
2. after it's done, insert the card to new switch.
3. dir slotx ; makesure you have the new file on it.
4. copy slotx: bootflash:
5. then do the boot system flash bootflash:YOURNEWIOS.
HTH,
lP.