Step 3:  Once restarted, check in SwitchResX preferences to see if the custom resolution has been installed.  If so, connect Macbook Pro to the M50-C1 (or other M series) to HDMI Port 5 using the CAC- 1170 and HDMI cable (18Gbps capable).  Use SwitchResX to change the resolution to either 1080p @ 60Hz (HIDPI aka Pixel doubled) or 3840 x 2160 @ 60 hz (native res).  Hold your breath and it should let you finally use your Vizio M series at 4k 60hz.  Check refresh rate by using the UFO test (www.testufo.com/#test=framerates)