Cura offers a platform support type of “touching buildplate” which enables the printer to only make a raft for parts of the object that should be touching the build plate. It also offers “everywhere” for any object that might be hanging over the build plate.
I have a need to only offer support for overhangs up to a certain z height, such any overhang located at a z-point of 4mm or below. Is there a software that will enable this, either as a setting/addition to Cura or just a G code export for pronterface?
Is there a software that will enable this?
Yes, as of Cura 3.3 Beta, Cura allows you to specify an area which will not be considered for adding supports. In your case you could define everything above 4 mm to be excluded from building support structures.
You can look here for this very new feature, it might be what you're looking for.