a root usb port usually has about 500mWs (thats milli.... not mega) of power.
most cd writers use about 300mWs of power. so theoretically there is enough power, but as discussed there are voltage issues. you could wire in a transformer, if you were in an uber hack kinda mood, but that would up the power requered and i doubt the end result would be all that portable.
(also high power devices are not all that good for your laptop battery life)