A kind soul (Canadian no less) built a easy to use webpage to help you set up your PPTP based VPN.
Please follow the steps on the following page to get your PPTP server-side completed.
http://www.andyhuang.net/tools/buyvm/pptpvpn.html
This guide isn't quite up to date on the last batch of US VPN changes we made to our network.
Other than that, the guide will hold your hand through the whole process.