I have installed Transmission on my Gentoo 2007 Kuro HG, runs well, im real happy with it, it takes a clean zen type approach, no feature bloat.
The install is straightforward providing you unmask the unstable package in Portage.
I could not get the stable version to start (1.22) you will need at least version 1.33
Do the following:
nano -w /etc/portage/package.keywords
Add this line, to unmask the current version:
emerge -av transmission
Then follow the rest of the guide from the "Configuration" step here: http://trac.transmissionbt.com/wiki/HeadlessUsageGentoo