If you cannot install any packages now (airport internets have issues sometimes :P), but have installed kernel power 47 (you have file /boot/zImage-2.6.28.10-power47 and directory /lib/modules/2.6.28.10-power47 on your device), you can manually add multiboot entry. Just create file /etc/multiboot.d/02-temp.item with contents:
If your /boot/zImage-2.6.28.10-power47 file is named differently (e.g. you have old power46 kernel and /lib/modules/2.6.28.10-power46 directory) you can change the contents of file accordingly. Basically, you need to have kernel named /boot/zImage-$ITEM_KERNEL or /boot/vmlinuz-$ITEM_KERNEL and directory with modules named /lib/modules/$ITEM_KERNEL (if you know bash scripting, this shuld be enough information, if you don't know anything about bash scripting, please don't continue because you can end with device messed up and not booting anymore. Instead wait with fixing it for better internet connection, then type as suggested previously: as root.

Edit: And, one important thing. Package "multiboot-kernel-power" is just an entry in multiboot for kernel power (as stated bazillion times earlier). You are not uninstalling multiboot while uninstalling it. Multiboot's package is named just "multiboot". All other packages named "multiboot-blahblahblah" are just additional stuff to it (like kernel images and entries in multibootboot menu) and by removing them you are not removing multiboot.