Part Usage table customization

I am trying to set the component for an attribute in the Part Usage table, or possibly in the Edit Usage Attributes dialog, to a dynamically created list of values that the user can select from; but, I'm having trouble finding any customization hooks that will allow me to do this.

I can set a data utility for the attribute on the Edit Usage Attributes dialog, but it is calling getPlainDataValue instead of getDataValue which seems to just call toString on the object I return and uses that as the attribute value.

Any help would be greatly appreciated.