How-To: Install and Setup a Network Print Server on your Asuswrt Router

Installing CUPS directly on the wrt linux router with these instructions

I was planning on installing CUPS via entware on my Asuswrt router.  It was a FAIL, but I documented my progress for reference.

How-To: Using a USB thumb drive with an Asuswrt Router

Format and partition it directly on the wrt linux router with these instructions

Running a modified version of the Asus firmware (Asuswrt-Merlin), you can plug in the USB flash drive directly into the router, ssh in, send a few commands and you're up and running.