Hi, I have also been trying to get my W540 to work with Sierra. I could enable the battery thanks to you. But I am still not able to get my display work with HD4600 properly. I was facing problem even during the installation as the screen would go blank before mac installation starts. Following RehabMan's suggestion I changed ig-platform-id to something invalid which led me to succesfully install Sierra. But with the invalid ig-platform-id I only see 7MB Video memory. If I use 0x0a260006 as ig-platform-id, the laptop screen goes blank. Did you face such issues ? Full details of my problems - https://www.tonymacx86.com/threads/lenovo-thinkpad-w540-sierra-installation.231567/page-2.
I am using below config from RehabMans repository -