I've done the beta 2, too. I will only link to our howto for firefox-3.6. The only difference are the sources. And I will offer the binaries of course.

You get the sources of version 3.6.beta2 at ftp://ftp.mozilla.org/pub/mozilla.org/firefox/releases/3.6b2/source/. You need to download ftp://ftp.mozilla.org/pub/mozilla.org/firefox/releases/3.6b2/source/firefox-3.6b2.source.tar.bz2 (perhaps you need a right-click here to get it).

[Yes it's German and the beta1. Please be assured that the US version is in English and up to date. I'm just a little bit too lazy to run and shoot the latest US-Version.]

The sources are compiled as I described in Firefox 3.6.x Community Build for PowerPC Linux.

If you prefer to use the binary, it's here: firefox-3.6b2.en-US.linux-powerpc.tar.bz2

If you need information on how to use the binary, please refer to Firefox 3.6.x Community Build for PowerPC Linux.