The older FAQ is now available here.
Why won't my kernel boot?
More than likely you didn't use one of the existing PlumpOS kernels' config file as a base
configuration for the new kernel. Just download one of the kernel packages, copy the 'config'
file into your new kernel source's main directory as '.config', and run 'make oldconfig'.
Then continue to configure the new kernel as you would normally and you should be set.