Cloning this repository:

git clone git://gitorious.org/android-on-freerunner/platform_packages_apps_calendar.git platform_packages_apps_calendar
cd platform_packages_apps_calendar

Add this repository as a remote to an existing local repository:

git remote add platform_packages_apps_calendar git://gitorious.org/android-on-freerunner/platform_packages_apps_calendar.git
git fetch platform_packages_apps_calendar
git checkout -b my-local-tracking-branch platform_packages_apps_calendar/master_or_other_branch