Start here:
http://forum.ppcgeeks.com/showthread.php?t=33857
Read, read, read. Not just the first few posts but as much as you can before your eyes cross. Then go back later and read more. Follow the clear instructions in the post. Download BuildOS and cook! A suitable ROM and all the programs you are looking for are available in the PPCKitchen.
Read the other threads in the Stickies section as well. All the questions you will have were asked before and answered.
Happy cooking!