Creating a VPN server compatible with Cisco VPN hardware?
 

I'm trying to set up a VPN server for someone with a Cisco VPN hardware box, and there doesn't seem to be a simple solution. OpenVPN won't work at all because the Cisco box needs to use IPSec and OpenVPN is an SSL solution. I can't seem to find a good solution for IPSec VPNs that will work with Cisco hardware -- openswan doesn't seem to work, and I can't find anything else.

Can anyone point me to a good resource for finding out how to do this? Is it possible?