The only way to do this is AFAIK to run your VPN and the programs you want to tunnel inside a VM. While it has a little overhead, it is an easy-to-setup way and you have the 100% guarantee that only those programs inside the VM are tunneled, since the VM uses a completely separate network connection from it's host. Just download one of the following freewares:
Oracle VirtualBox
VMWare Player
Windows Virtual PC