If you use Keyclone, you can set this up with hotstrings/keymaps. I have a 3box on EQ2 where a ctrl & arrow keys will move the left slave while alt & arrows will move the right slave. Un-modified, the arrows will move both slaves together (though typically in different directions, but great for moving into or away from a mob).

Normal movement is still of course done via WASD & /follow. Hope this helps