There isn't numeric entry for vertices, sorry. In many situations eyeballing it is sufficient, though I know there are times where more accuracy is needed.
You could create bones for each vertex, zoom in and place the path vertex as close as possible to the bone position, then use the Weights view to bind the path to the bones. Weight the vertices 100% for the corresponding "vertex" bone. Now you can place the bones numerically and the path vertices will match.
Another thing you can do is to not rely on the placement at the end of the path to be exact. When attachments moving along the path reach the end, you could stop using the path to control the placement of the attachment's bone. Ie, change the path constraint mixes to zero and set the bone position explicitly.
