How can I implement the Modulo function in VBA?

VBA 2003 does not support MOD (modulo arithmetic) as a WorksheetFunction, and there does not seem to be a direct MOD function in VBA. I've been dabbling with code that would do the same thing as MOD, so far with no success. Does anyone know how to do this in VBA? I assume it would be some combination of If...Then, Round (up or down), maybe a compare, and perhaps an iteration loop. I would think such a routine would be useful to many people.

Thanks in advance.