I greatly encourage you to start from scratch and use U-boot, instead. kernel-power dropped support for multiboot some time ago (.item file isn't multiboot-compliant anymore), so you would end up with problems, even if you *wouldn't* forget to install bootimg.

Anyway, u-boot is much better solution than multiboot, and can be considered replacement for all intents and purposes (not to mention that u-boot is capable of many others things, too - but, even if you don't care, it for sure can do everything multiboot offered you, and does it better).

/Estel