It's strange that the installation program didn't find a kernel, did you check the iso images and the installation media? As for chrooting and installing the kernel, I guess it should not be difficult, in case it's the only thing missing. Assuming your Debian root partition is /dev/sda1, you can try this from a live environment or other Linux install on the same computer:
mount /dev/sda1 /mnt/debian
mount -t proc none /mnt/debian/proc
mount -o bind /dev /mnt/debian/dev
chroot /mnt/debian /bin/bash
apt-get install linux-image-2.6-your_preferred_architecture
While on the chrooted environment, you probably have to update grub's configuration in order to add the newly installed kernel (in case grub is installed):
Hope it works.