Yes, it can be done. Since Macs aren't supported officially by Cisco, a community has grown because of it. On their intranet there is a great forum with lots of answers on how to get your Mac working with the Cisco VPN network. The answer to this question was not there though, I checked. I did see a how-to of how to connect via VPN using the built-in Apple tools. I would link to it and show you, but I can't since it's on the intranet.