I just tried this:
Copy whatever .cap you want into the <Templates> directory, and rename the extension from cap to cst. Create or copy one of the current .bmp files and rename it <your template name>.bmp.
You should then have 2 files, same filename with extensions of ,bmp and .cst.
Start CC, select New Template and there it is. Worked for me.
If your vision so exceeds your ability, then look to something closer.