What I usually do is I use my sony digital 8 camera and capture it from there since it has firewire. I'm not sure if they make digital 8 decks. If they do it would probably cost alot. You're best bet is either to get a analog converter or a find someone who has a digital 8 camera.
Yep, use a digital 8 camera for the easiest one-step solution.
If you have a regular 8mm video camera and a DVX, you can still do it, plug the analog output of the 8mm camera into the DVX's analog inputs, and set DV OUT to "on", and the DVX will automatically convert the 8mm's output into firewire on the fly.