I feel the same way about clamps and although I use Limb Drivers on my bows, I do set up bows for friends that use down cable powered rests.

1. Press your bow and split the cable evenly.
2. Leave the cord long running through your cable.
3. Unpress bow and draw it. The cable strings will hold the cord good enough to let it slide through after it has engaged the rest, thus leaving it at the right position to begin serving.
4. I serve mine from the top down and then when I get to the non rest side, I serve that right against the cable. It give it a real clean look.
5. When done serving, cut your excess cord and melt end to prevent fraying.

Here's a terrible cell picture I just ran down and took of a friend's back up bow that I did this too.