Installing mmc-get
$ git clone https://github.com/jrfondren/mmc-get.git
$ cd mmc-get
$ git checkout v0.1.1
$ make install

-or-

$ git clone https://github.com/jrfondren/mmc-get.git
$ cd mmc-get
$ git checkout v0.1.1
$ mmc --make mmcget
$ mv mmcget ~/bin/mmc-get

-or, if you are using Mercury 14.01-

$ git clone https://github.com/jrfondren/mmc-get.git
$ cd mmc-get
$ git checkout 14.01-compat
$ make install

NB. as of v0.1.1 mmc-get assumes a Unix environment with wget, git, and fossil as needed.