Here you can find some links to howtos for using PHC.
If you have your own howto or if you know a good one just send me a pm and I will add it here.
Undervolting in Ubuntu 10.04 (Lucid) LTS
by Dan Mihai Ile
http://openmindedbrain.info/09/05/2010/ ... lucid-lts/
Undervolting your CPU on Debian Squeeze
by o0arthur0o
http://o0arthur0o.wordpress.com/2010/06 ... n-squeeze/