I don’t know of any HOWTOs off hand regarding power management — you’ll have to look at Atmel documentation for the processor and at the driver, which is located at <linux src>/arch/arm/mach-at91/pm.c in the kernel source.

The easiest way to incorporate your changes into the CoreCDP kernel build is to generate a patch and add it into the kernel recipe. The location of the linux recipes varies depending on which CoreCDP version you are using. The 1.1.1 linux recipe is openembedded/recipes/linux/linux_2.6.32.bb. The 2.0.2 linux recipe is multitech/recipes/linux/linux_2.6.35.bb.

To generate the patch, I recommend looking at the ‘quilt’ tool. Or you can just use diff directly.