It's possible but very messy to do this.
Set up a virtual machine in VMWare (or any other vm tool) that can connect to your PPTP VPN. Set up a SOCKS proxy in the VM. Install Proxifier (or a similar tool) on your host computer and configure it to redirect all ports that you want to send over your PPTP link through the SOCKS server running inside your VM.
Unless you have very specific needs, however, it'll be less hassle to run all programs that you want to use your PPTP link inside the VM rather than mess with the added SOCKS layer.