If you want to write a custom configuration, or don't want to use the HDAconnect tool, this will help you set up OpenVPN on a Windows XP/Vista/7 machine, without much of a problem if you have the default settings for Amahi installed and your port forwarding set to 1194 UDP.

Launch OpenVPN GUI, and you should be ready to go. Right click on the Icon, select the config file you wrote, connect, log in, and enjoy.