If I understand that right, you're asking for a command to shift/rotate your char relatively to their present coordinates.
Finetuning beyond the normal walking keys, so to speak.
I actually like that idea, since especially sitting down precisely is not easy.
![Smiley :)](https://www.hydlaaplaza.com/PlaneShift/smf/Smileys/custom1/smiley.gif)
But there should be a cap of allowed movement, preventing you from sliding under the floor, up unclimbable houses or
into other normally unreachably places.
(Item drop already allows for finetuning by mouse.)