^^Marcusrav, I have done it as well, it was not that hard at all (MUCH easier than some other PITA phones I have done). You just download all the files needed, run the .EXE on your computer, select the right settings and hit GO. Afterwards you just need to use the recovery to push the SuperSU app (SuperUser would probably work as well but SuperSU works for sure) and you are good to go. You dont need to mess with disabling the KNOX program (at least I didnt) as I dont think the Metro GL comes with it.
The ONLY things that could mess you up would be to make SURE you have enabled "USB debug," which just involves going to the "phone status" and hitting the "build" area (I guess you would call it) like 7 times to enable the developer options and then going into that and enabling USB debugging.