[Chriszuma]

Well they do make stranded cat5 cables (they're the expensive kind), but the color thing might be a problem. cat5 cables normally have blue, green, orange, and brown, as well as their striped alternatives.

EDIT; Here is the rule from the manual:
<R81> All wires distributing power with a constant polarity (i.e., except for Relay Module, Speed Controller, or
sensor outputs) must be color-coded as follows:
• Use Red, White, or Brown wire for +12 Vdc and +5 Vdc connections.
• Use Black or Blue wire for Common (-) connections.

You can use the brown wire for positive, and the blue wire for ground, and you're good to go. It doesn't say anything about not having an extra layer of insulation over all the wires.