Time integration of calculated value

I am trying to perform an energy balance calculation in Process Book.  Given the generation, I want to use a simple calculation to estimate the auxiliary load and than time integrate this value to calculate an estimated auxiliary load MWh.  I can use a calculation like TagTot('Gen','t','*')*24 to do the calculation for generation for which there is an existing tag.  How do I use the TagTot function to calculate MWh based on a calculated value like (0.03*'Gen'+0.3)?