Or, a variation of Doug's idea(?), move the origin of the cube to the center of
the far side that will be in front of the camera in MED. Then assuming the cube
is say 20000 per side, the cube should be kept 10000 quants in front of the
camera so the camera is still in the center of the cube and the cubes origin is
always 10000 quants in front of the camera. (like this;)

Code:

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action tint_cube
{
 while(me)
   {
     vec_set(temp, vector(10000,0,0)); // create offset with temp
     vec_rotate (temp, camera.pan); //pan temp same as cameras pan
     vec_add (temp, camera.x); // add cameras position to offset
     vec_set (my.x, temp.x); // put me there
     wait(1);
   }
}

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