1.Insert the OSX Software Install CD or DVD.
2.Restart your computer.
3.Hold the "C" key until you have booted from the OSX Software Install
4.Select the Install menu at the top of the screen.
5.Select 'Open Disk Utility'.
6.Select Mac HD (or the name of the drive that contains OSX).
7.Select the Partition tab.
8.Under the Volume Scheme menu, choose "2 Partitions," one for OS X and one for Yellow Dog Linux.
9.Select the first (top) partition, "Untitled". It should be gray.
10.Use the Format menu to the right and choose "Free Space." This will be your YDL partition.
11.Move the slider at the bottom of the partition to increase or decrease its size or, alternatively, enter your preferred size in the Size text box to the right.
12.Select the second partition. This should be your MacOS X partition. Keep it OSX Extended, and resize as desired.
13.Name this partition "OS X" or whatever you like.
14.Click the "Partition" button at the bottom of the screen and then again at the prompt.
15.Quit Disk Utility.