Note that these packages will not work with any version of Sublime Text older than Dev Build 3092.
If you wish to make any changes to these and test them locally, the simplest way is to fork the repository, and then symlink the package(s) of interest into your Packages folder, e.g., on OSX:
$ git clone https://github.com/sublimehq/Packages.git
$ ln -s `pwd`/Packages/Python ~/Library/Application\ Support/Sublime\ Text\ 3/Packages/PythonAfter you've finished, keep in mind that you're now overriding a default package, and when Sublime Text updates to a new version, unless you pull the latest changes from the repository, you'll run the risk of having an out-of-date package.
On Windows, rather than fiddling around with symlinks, the simplest approach would likely be to download the portable version, and clone this repository directly as a subdirectory of Data.