As others said, it did indeed prove to be the case that current versions of glibc
do require a Linux 2.6 kernel to be running in order to complete the installation.
I proceeded to download, configure and install a 2.6 kernel, running on my current host system, using either
compiler that I had already downloaded to the lfs
the one that was already installed upon the host.
As predicted, it turned out to be important to build a "module free" kernel. That is, one in which all of the necessary functionality was built into the kernel and always-resident. And by the way, you'll be rather startled at how much faster this kernel runs than the one you've been using.
I made extensive use of a series of articles at http://www.LinuxDevices.com/articles/AT3855888078.html
for pointers on how to support booting of the "old" (host) kernel or the "new" (2.6) kernel on the same system.
From then on, you can proceed with the LFS instructions pretty much exactly-as-stated.