- straight, female-female cable (seriously check that it's straight, pins 2 and 3 must not be crossed)
- serial port (TTL-level devices don't seem to work - at least it didn't for me - so make sure it's a real RS232)
- some terminal program, putty works well enough
- select the right COM port, 9800 baud, 8N1...the bog-standard for slow serial
If you see text while the switch is booting, you're golden. If not, something is not working the way it's supposed to.
Before you can start wreaking havoc in the console, you have to wait for the switch to boot. There is a procedure to get console before boot, but that is generally useful only if you locked yourself out.
Once you get the ASCII-art logo, press CTRL+y, then type "en" or "enable". Let the typing begin.