If you need to install it manually, apt-get install pulseaudio should "just work" in every release since Debian 6 (Squeeze). PulseAudio becomes the default when the package is installed. Everything will use it. This can be checked by with pavucontrol (in the pavucontrol package). If the sound is registering in the vu vumetre of that program, then it is being routed through the pulse system. Basic