How to include packages from the testing repository to a stable installation of Debian Linux using a technique called Apt-Pinning.

Add New Repository

Include new staging in /etc/apt/sources.list:

deb     http://cdn.debian.net/debian/ wheezy main non-free contrib

# new:
deb     http://cdn.debian.net/debian/ jessie main non-free contrib

Configure Pin-Priority

Create new config file in /etc/apt/preferences/:

Package: *
Pin: release a=wheezy
Pin-Priority: 100

Package: *
Pin: release a=jessie
Pin-Priority: 50

Update Dependency Tree

Run apt-get update.

Install Debian Package

Try to install new package using this:

apt-get install newPackage/jessie

If this fails with dependency problems, try this instead:

apt-get -t jessie install newPackage