I get an error when I run Mediacost.cmd. "'subincl' is not recognized as an internal or external command,..." subincl.exe is installed in the proscribed tools directory. I am running it as admin. I'll recheck the second link from foxbrook to see if I missed something.
I just ran through the instructions from the cnet article and I did get it to work. Follow the instructions exactly. I goofed up on the permissions setting the first time around.
I'd also strongly recommend you back up the registry before making the changes.
I recently came across a third party app called Winaero Tweaker that has a switch to set an ethernet connection as metered. I've found it to be a lot more convenient than using regedit.
Remember to re-visit that setting after each and every Windows Update as those tend to reset core Windows setting to default values in a much different manner than previous MS update behavior.