[Akoppenheffer]

With the Redeye, you want to take "mic level" out into a mic preamp, just like you would with any microphone. The mic level isn't hot enough to just go into a line input, and you have no control over the signal. So just treat it as if it were a microphone. Turn up your preamp until you see a good level in Pro Tools. When going the other direction, you're right, line output into the Redeye's "line input" and then "reamp out" to the guitar amp using a standard instrument cable. Watch out for the di/reamp button on the front.

EDIT: psycho monkey beat me to it...