Novice Question (dimensioning)

I am an absolute beginner in Solidworks. I have managed to create parts, combine them into an assembly and to calculate the center of mass. My problem is that I have no idea at all of how to show distances to this point on the drawing. The CM is a point in space that is not on any physical feature. The result that I'm trying to achive is a drawing showing my assembly with dimension lines from the origin to the Center of Mass. (Solidworks 2003 SP3.1) Thanks in advance for any and all help.