From Wye Waltz Wiki
Access to the top of the path is from the Welsh St car park, the large car park for upper Chepstow, through a stone archway in the Town Wall. Access to the bottom of the path is by following the castle wall to the left of the entrance.
Just at the top of the castle, there's a small viewpoint over the river.
Disabled access to this footpath is not good. The surface is good, but it's steep in parts.