...I have successfully established a LAN-to-LAN VPN connection using our two Cisco 3020 VPN concentrators. I've, quite literally, been struggling with this for weeks on end, so it was quite gratifying to get it working. There are a few minor routing issues that I still need to fix, but those will be easily overcome.
As a sidenote, considering how large of a company Cisco is and considering the high-quality equipment they make, it's amazing how little documentation there is out there for their products. I suppose they're trying to get people to sign up for their certification classes.