I was going to say that you can do that if you have C3D 2007 or earlier, and that the ability was removed by Autodesk in C3D 2008.
But then I started up C3D 2007 in order to create the sort of label you want, and I discover that it was impossible in C3D 2007, too. There is no way to create Reference Text to Points in C3D 2007 General Note Labels. The only options that are available are Alignment, Profile, Parcel, and Surface - no Point reference text.
So I think you're out of luck on this one.
If you tell us what you're trying to do, we might be able to come up with something else that will work...