It's been a while since I've played with this stuff on my RT-N66U but here it is:
https://forums.mydigitallife.net/thread ... rms.50234/
https://github.com/laggardkernel/vlmcsd-magisk
You can also get binary files to start automatically from a USB stick on boot:
http://irq5.io/2012/12/10/hacking-funct ... t-routers/