Ive already reset my catalyst 3550, but im lacking a straight cable to access the express setup function. I have a roll over cable and a standard crossover. is it possible to use either one instead? if so, how?
Are you talking about a console cable? These are not ethernet cables.
You can use one from a router, or in a pinch, jury-rig your own.
The Express Setup expects you to have a working Ethernet connection to your switch. As the 3550 Catalyst series do not have an autocross capability on their ports, there are only two options: either your notebook or PC already has a network interface card that can do autocross in which case you will be perfectly fine with the standard crossover cable, or you are sadly out of luck and definitely need to get a straight-through cable.
To put it simply, try using the crossover cable to connect your PC/laptop to any of the Ethernet ports on the switch. If the port comes up, you can safely proceed with the Express Setup. If the connection does not come up (the port LED remains dark), you will need to get a straight-through cable.