I just followed README.md, there is any modification I didn't any modification except SerialNumber, USB PID/VID, MACADDR on bromolow_user_config.json .
If you no have any Intel NICs on your N54L, additional driver (eg. tg3.ko) needed.
Basically DSM does not support (exactly not included) Broadcom NetXtreme.
But I don't know how add additional driver to boot image, so I added Intel NICs to my N54L.