You use a RS232 cable, one end plug into the serial or config port of the NetApp controller, the other end plug into the serial port on your computer or laptop. These days, most laptops don't come with a serial port any more. In this case, then you need a USB to searial port converter (it's an adapter with a CD with some software you need to install). Once you have the cable hooked up, use Hyper Terminal (comes with Windows), and configure the session (select the right COM port, set baud rate, etc.) Once that's done, you should see a NetApp controller interface inside the hyperterm and you can configure the controller from there. If you have not done this before, probably it's a good idea to ask someone to help.
Alternatively, you may still have telnet access to the NetApp controller. I think the disabling of http only disables the GUI. If so, then it's easier than using the RS232. Please let me know if you can access the controller via telnet.