OK, if I were you, I'd do this.
All the cell has power arc in the library and I'd find a way to get power consumption from each of all the cells that belong to the pipeline I'm interested in, while running simulation.
First, writing a script(DC, perl, python.... whatever works) to extract all the instances between certain flops.
Second, getting transition times and caps on all the nets belonging to the given pipe stage and looking up the power arc to get the power from each cells you extracted and sum them up every cycle. That's a power consumption only from the certain pipe stage.
I'd think there should be a command to get a power number for an individual instance. If it doesn't have one, I'd write a script to get transition times and cap on all the nets in the give pipe stage and consult with power arc in the lib to get a power number.. And repeat this for all the instances and sum them up..