I used the formulas on the first 4 or so pages:
http://www.gamefront.com/files/23015...s_Only_TMA.rar
to calculate the AOB at the first bearing (of 3) to make this slideruler/disk:
http://www.subsim.com/radioroom/showthread.php?t=147719
The DRM or Direction of Relative Movement, aka target course IF you yourself are not moving, is then just a matter of adding/subtracting some angles.
I think your best bet is to construct everything with vector-magic.