5V+ Supply for Gecko?

Last Gecko message for a while, I promise! :)

I've scoured the Gecko docs and circuits online, but I still have a
question about Geckos and grounding/voltage. I've cleaned out an old
computer case to use as my servo driver box, and this gives me a nice
12v/5v power supply I can use for logic and driving 12V devices
(relays/cooling pumps etc) anyway, now I'm wondering if it wouldn't
have just made more sense to run a 5v power cable from the computer
to this box?

The Gecko manual says it wants 5V+ from the controller, it shows this
running through the opto-isolators and back to the STEP/DIR pins. I
was wondering, is it possible to just get this from a certain
parallel port pin? Or do I definately need a wire running from the
controller PC to gecko? Also, what's the deal with the encoder power?
Does it get this from the controller too (ie, will I need to connect
the controller ground to the ground pin on the gecko?) or does the
gecko use a voltage regulator internally to produce 5V from the 18-
80V power supply input?

I guess what I'm saying is, can I get away with using the 5V power
supply in my servo-box, and getting 5V from the parallel port,
without needing to run an extra wire from the PC?

Thanks!
~Abby