Is it possible to route only a specific application through a VPN?

I've recently purchased a VPN from vpntunnel.se and was wondering if it was possible to use it for specific applications (Firefox, xchat etc)

Also i'm having a little trouble setting up the the VPN in Gnome's Network-manager, I have the network-manager-openvpn package installed but it keeps complaining about "no secrets"?

I can connect fine with the console client and the GUI KVpnc

Thanks

You can, but it's complicated.

Keeping it brief, the way I'd do it would be to run a SOCKS proxy on the local machine, and configure it to push traffic out down the VPN interface. You then configure each of your applications you want to push traffic down the VPN to use the SOCKS proxy. If they don't support SOCKS, of course, then you're out of luck.

On the other hand, if the applications you're using only need to run traffic down the VPN to certain locations, you could modify the routing table on your machine to route traffic to those locations through the VPN interface.