BlackBox: how to make a TD Tool (modifier stack) variable for the input nodes for Matterwaves. It has a node parameter, but it only allows for a single object selection. The default node selection in the Matterwaves interface has a list selection. However, if you expose an object list selection in the modifier stack, you cannot pipe it into the node selection of the Matterwaves.
Create a custom Maxscript that collects all Matterwaves operators in the currently-selected Thinking Particles and this gives you an interface to add/remove objects from that list... assuming Matterwaves _has_ that MXS function. There's a good chance it does because Obj2Particle has such a function.