Hm...just a theory here, and I don't know how possible it is, but...
Edit: the down-side being, other than an added graphical mod to the map frame, that you'd have to maintain two PoI lists, which would seriously complicate things and increase the risk of one or the other being out of sync.
Edit2: Editted for clarity...I hope.
Really bad ASCII art example:
A B C D E F G H
Say I search for the 'x', the Inventory.HTML window would return Commonlands (East) D4, while the '^' would return Commonlands (East) G3 and so on.