The first thing that you probably want to do is read up on rotation matrices. Rotation around the z-axis (axis coming out of the screen) is handled by the following logic (courtesy of dELta):
//all coordinates assume a desired registration point of 0,0
x2 = x*cosA - y*sinA;
y2 = x*sinA + y*cosA;
// if the desired registration point is not 0,0 simply change to the following (I think this will work, didn't test it):
x2 = x-xo*cosA - y-yo*sinA+xo;
y2 = x-xo*sinA + y-yo*cosA+yo;
where xo and yo are the desired rotation points.
If you are rotating a movie clip rather then a simple point, the pseudo code above will only rotate the object around a point as if it were a particle (IE no rotation, only displacement). Simply change the MC's rotation property by the "A" value to achieve the correct rotation.
Since I helped you, maybe you'll give me an idea now :P