How do I correctly install the tools in git's contrib directory?

Git includes a set of tools contributed by third parties. I'm not sure how I'm supposed to use these tools correctly.

For example, I'd like to use git-subtree. There seem to be a number of ways I could use this:

1. Copy to my path

    cp /path/to/git-subtree.sh /usr/local/bin/git-subtree
    chmod +x /usr/local/bin/git-subtree
   

   Works fine, feels a bit hacky.

2. Symlink to my path

    chmod +x /path/to/git-subtree.sh
    ln -s /path/to/git-subtree.sh /usr/local/bin/git-subtree
   

   Also works, feels marginally less hacky

3. Use a git alias

   Add the following to my global .gitconfig file:

    [alias]
        subtree = !/path/to/git-subtree.sh
   

   Then good old chmod again:

    chmod +x /path/to/git-subtree.sh
   

   Works, feels all nice and git-ish.

4. Use the Makefile

   Per the INSTALL file.

    cd /path/to/git-subtree.sh
    make
    make install
    make install-doc
   

   Doesn't work for me, it tries to install to a non-existent path. Perhaps this is because I installed git using homebrew rather than installing from source? I'm too lazy to investigate; I already have three working alternatives. :)

So my question is, which of these is the preferred way of installing git-contrib add-ons? Is there even a preferred way? Is there another option I haven't suggested that's better than the ones listed above?