You are able to do that within VNL, of course.
If I understood well, not sure about that, you simply need to open your ELF analysis with the Viewer and choose cut-plane option.
Drag and drop your structure in the same windows afterwards.
Select the atoms that you do not want to visualize and set opacity to zero.
Now possibilities are endless, also considering some new visualization options of VNL 2015 (third beta version available for download from our website).
See screenshots with examples for ELF of graphite.