codec guides, where?

[posix]

i am looking for step-by-step guides on configuring various codecs. have searched doom9 for a couple of days but it's too huge to really find anything.
this xvid guide is a perfect example of what i'm looking for. http://ronald.vslcatena.nl/docs/xvidfaq.html

i'm interested in any codec really, particularly divx6, realmedia and x264.

thanks in advance.