[phenixbb] Isolate Protofilament from helical reconstruction

Dear PHENIX mailing list, I have a question regarding a helical reconstruction, done in cryoSPARC. Usually, I work with "normal" symmetric particles, and there I can simply run phenix.map_box to isolate the asymmetric unit. This is somehow not possible with a helical map. As we also don't have an atomic model yet, we cannot just crop it with map_box. In our helical reconstruction, we have helical twist (in degree) and the helical rise (in Å) and a additional point group symmetry. We would like to isolate a single protofilament for further model building. Is this in principle possible in PHENIX? Additionally, is there a way to rebuild the helical structure, analogous to apply_ncs? Thanks Christian