Question HDRP Layered Lit - Blending between multiple materials at run-time

Hey there, I'm trying to blend between several materials at run time and stumbled across the layers lit shader for HDRP.

This is almost what exactly I need, however I need to change the blend between materials at run time dynamically - however the only way to control the visibilty of shaders in this shader is via a layer mask in the surface input. Is there anyway to edit this layer mask at runtime to get hte desired effect?

Thanks
Ant