How to get particles from 3D classification

I'm trying to work on the particles from one class from a 3D classification (similar to what one would do with selecting 2D class averages). Is there a straightforward way to do this? I tried exporting the Refinement Package using the parameters from the class of interest, but that output all the particles, not just the particles belonging to that class. I tried then to use merge_classes.exe from Frealign, but that said that the parameter file was incompatible. I'm sure I can hack around this, but is there an easier way?

Thanks,

Scott