AbleCommerce Shopping Cart Software

I'm doing some customising of 7.0.2 and want to allow the user to input a shipping message on the OnePageCheckout screen. I can see code referencing the ShipMessage but can't see how to get it working. Has anyone looked at this or has hints on how to go about it?

Thanks

John South

Edit OnePageCheckout scriptlet and change the ConLib reference as below
[[ConLib:OnePageCheckout EnableShipMessage="true" ]]