You should just be able to run a cable from a port on one switch to a port on the other switch, though it will probably need to be a crossover cable. The only things that might cause problems with doing that, AFAIK, are if they have port security enabled on the switches. Port security can limit the number of MAC addresses coming from a port, to prevent people from plugging a switch or a hub into that port. Also, while it shouldn't be necessary, it would probably be a good idea to make sure that the ports don't have spanning tree disabled (no port fast), and are set to auto-negotiate. Assuming that the SFP's are the same it should work fine, though I've not actually done that myself. Really, there's not a whole lot you could hurt by just plugging it in without changing any configuration. The worst case scenario is that it doesn't work, and you have to look at the configuration on the switches.