Ok, this post come with 2 warnings:

1) I don't know if this has the functionality you need (Cisco can use keys, vpnc doesn't yet support that, as far as I can tell)

2) I compiled this myself, and it compiled fine, but I never tried using it

I was compile happy when I first set up the scratchbox for 2007 a while back. I compiled VPNC (the current version at the time was 0.5.1, I guess). I noticed that vpnc available in the repositories was 0.3.2 I think. I knew that version didn't have the functionality I wanted, and just wanted to try 0.5.1. It compiled, but took over 18 seconds to get it to my n800 (the limit of my attention span), so I forgot to ever try using it.

If it works... great. If it doesn't, I'm really not the person to ask questions about this. But since I saw your post, I thought that maybe you'll find this helpful. More likely than not, I'm just posting crap. Sorry, if that's the case.

YOU ALL HAVE BEEN WARNED! (I'm certain it's not going to screw up your machine or anything. It'll work or it won't. Not even sure if it will work under 2008).