This is going to be somewhat difficult for you. As of now there are no installers for PPC based PC's. On a positive note I have a compile guide specifically for feisty fawn that is easy to use.
http://vaalnor.mine.nu/psdoc/?q=node/43You will eventually get to a step that looks like this:
wget http://download.nvidia.com/developer/cg/Cg_1.4/1.4.1/Cg-1.4.1_x86.tar.gzSkip this step. There are no bins for the cg libraries for PPC processors so do not install this. The above file is for x86 processors only, which yours is not. This might lead to some minor graphics problems on your system but you should still be able to build a fully functional binary on your own with minimal fuss.
There is another catch. You will have to get a copy of the artwork somehow since the mirrors are currently down. The part about running the updater should be ignored for you. I'm up very late and I apologize but I will have to make you a tar file of the art later - probably tomorrow and link you to a download. Don't worry though, we'll get you through this. It all sounds daunting but with a little patience you will be up and running and you'll learn things along the way!
If you want you can go ahead and compile before the art is posted. you don't need it to make your binaries, only to play the game. Once you have compiled it all, all you need is to copy in the art and data and voila, working build. I'll make sure to include specific instructions on how to apply the art package at teh appropriate time. Lets get it compiled first though. Good luck, I'll check in and see how you are doing. If you run into snags or have questions feel free to ask them here.