I figured out how to do this.
In Cura, create the entry for your new material. (I just cloned generic PLA and changed the name, brand, color, etc)
Export the new material
Open the exported material in a text editor
Find the <machine> sections and then find the block for your machine.
Inside each <machine> section there are are <hotend> subsections.
Each of these will have a line like "<setting key="hardware compatible">yes</setting>"
For each hot end set the value to "yes" or "no" depending on if that type of print core is compatible with this material and save the file.
In Cura, REMOVE the material you created.
Now IMPORT the material from the modified file.
Sync materials to your printer as normal.
Now, if you select your new material on the touch screen but don't have a compatible print core loaded the screen will warn you.