I faced recently the problem, and solved it
without passing through FC3test, MacOSX or switching to YDL
The problem is that FC4 doesn't have a good DiskDruid porting tp ppc architecture and nor the CD1, nor the DVD version contain the only one good tool to do the partitioning job. The fdisk you find there is for x86 style partitioning and does not create the 2 partitions needed by the Mac BIOS (called Open Boot) to work properly.
To solve the problem you can use the CD1 of another distribution like Debian, Slackintosh (as I did) or YDL and use the tool called mac-fdisk, partition your HD makeing a "new empty partiton table" and a "Apple boot partition" first, adding the partitions you want afterwards . Reboot with the Fedora DVD and install without repartitioning, but selecting the mountpoints only.
YDL is not a good choice because packets are a little bit older than the one Fedora provides and some installing guides for YDL+ppc suggest the user to install YDL and some Fedora rpms afterwards (like Thunderbird and Firefox or OpenOffice) Notice that YDL includes OpenOffice 1.2 while Fedora-ppc provides 2.0 beta! Why should a FCL user switch to YDL??
I wrote a pretty complete and deep guide to install FC4 on an iBook (suitable for any other new world Mac); unfortunately only in Italian at present (Im from Turin, 2006 Winter Olympics City) Check the link because an English version is coming nsoon!
My guide is at: http://www.labinf.polito.it/nepote/l..._ibook_g4.html
Hope be usefull