SimpowerSystems conection with equation load

Hi there,

Maybe someone can answer me this...
I am working with the simulink library, SimpowerSystems, and in stead of a normal parallel RLC load, I would like to put one equation that characterizes my load. I know to create the equation on simulink, I know to create the circuit on simulink (with SimpowerSystems), but I can not conect them. How do I do that? There are some connector element?

there are any sugestions?

thanks in advance

Rudi