[bugwelle]

The error you get in your second post is because the "MediaElch" directory already exists

The error in your first post is the important one. I forgot that "make install" needs to be executed by an administrator.
So, in your Terminal, go to the downloaded "MediaElch" directory and then to the "build" folder.
I don't know where you downloaded MediaElch to (the source code was downloaded by "git clone ..."), so change the following path accordingly.

bash:
cd /path/to/MediaElch/build

You then only have to executed following command (because you already build MediaElch. The only thing left is to install it):

bash:
sudo make install

(note that I added "sudo").

You can also send me a private message if you still run into problems :-)

Regards,
Andre