How to create a custom cube map blend node

I’m working on a setup to bake out a grid of hdrs for skylight reflections and then blend them based on player x and y and time of day. I’ve got a test working in the material editor using lerps, the last piece is blending everything inside the skylight blueprint.
So what I need help with is either:
-a way to use the existing cube map blend node to combine the various input maps into a single output (the test is blending 2 on x and 2 on y for 2 time states (8 maps at any given time))
-help accessing and modifying the code for the current cube map blend node to make something that will blend more than 2 inputs