Q: How do I get pulseaudio to use alsa device other than default?
A: Package "alsa-plugins-pulseaudio" sets up pulsaudio assuming that each box is associated with one user, and that there is only one default soundcard one might use. In many instances, this is a totally incorrect assumption. For one, one may not want to set the first ALSA device found as the pulseaudio default. For two, a system might have multiple users, each wanting to use a different soundcard…
To rememdy this problem, I did following:
(1) Note that /etc/asound.conf loads /etc/alsa/pulse-default.conf:
(2) Note that /etc/alsa/pulse-default.com has code which sets the default PCM device to pulseaudio:

# Let's make it the default!
pcm.!default {
    type pulse
    hint {
        description "Default"
    }
}
ctl.!default {
    type pulse
    hint {
        description "Default"
    }
}

(3) Comment out the lines above forcing default Alsa device for all users, in /etc/alsa/pulse-default.conf
(4) Setup default device on per user basis via ~/.asoundrc. Other users might have different devices like pcm "hw:1,0" etc.

pcm.!default {
  type plug
    slave {
    pcm "hw:0,0"
      rate 48000
      }
  hint {
    description "Default"
      }
}
ctl.!default {
  type hw
    card 0
    hint {
    description "Default"
      }
}

For further reading:

http://alsa.opensrc.org/index.php/FAQ026
http://www.mythtv.org/wiki/DigitalSoundHowTo
http://www.gentoo-wiki.info/HOWTO_Jack
http://www.zen.org/~brendan/mythtv/asoundrc
http://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html
http://www.mail-archive.com/alsa-user@lists.sourceforge.net/msg21125.htm