These are instructions for modding USB for the WPN824N. I couldn't find any information on this so I'm sharing what I found.
Make the same source modifications as the DIR 615, but on mach-wnr2000-v3.c
Jumper F1 and D9 for power and L3 for ground. Install 22ohm for R9 and R10 and 15kohm for R13 and R14.
Jumper R18 and R19 to connect data lines to the SoC.
Example of a 5v power supply. This is just a car charger with the usb bits cut off covered in heatshrink.