If I understand him correctly (sorry for being the official/unofficial request interpreter for the forum, again), I think he means or meant a 'Slice' plane object like exists in 3ds Max - either as a modifier for 3ds Max proper, or as a separate render-time only object (like VRay has)
Corona in 3ds Max doesn't have this feature either, so it's doubtful it could be implemented here for ArchiCAD before it shows up in that program's plugin.
I believe (but may be wrong) that it's already been requested as a wishlist feature for the Corona 3ds Max plugin for future versions, so I'd pay attention to see if and when it shows up there in any upcoming version first, before showing up in the ArchiCAD plugin.
Just my opinion.