If you don't already have one, hook up a Webcam to your computer. Webcams can be purchased at any electronics store and have easy-to-follow installation instructions.
Test the Webcam by simply sending a video email, or getting on a one-on-one chat with someone to make sure you are able to see the other person and they can see you.
Discuss the idea of having virtual sex with your partner. Make sure he or she is on board with the idea before trying to spring it on him or her at a random moment. You can save the actual event for the sake of spontaneity, but at least get an agreement to try it before proceeding.
Plan a time to do it when both of you are alone in your respective locations. Assure your partner you are alone and no one can hear or see him or her.
Set your camera up so it's filming all of you at a relatively close distance. Sit on a chair or somewhere comfortable, making sure your partner can still hear you. Audio is just as important as visual.