Currently there are two available releases:
Install the MxM gpg key:
this requires root previleges
apt-key adv --keyserver 'keys.gnupg.net' --recv-keys '7F40EF0A'
run the following command, it will create a apt.mxmdev.com.list in /etc/apt/sources.list.d/
to install experimental packages run the following command
echo "deb http://apt.mxmdev.com unstable main" > /etc/apt/sources.list.d/apt.mxmdev.com.unstable.list
to install stable packages run the following command
echo "deb http://apt.mxmdev.com stable main" > /etc/apt/sources.list.d/apt.mxmdev.com.stable.list