I've been getting a few questions about this, so I'll mail this here
for the people who are just desperate to get Doom running ;-) :

The announcement posted to the announce groups shows which files you need,
but where to get them?

If you have access to a Linux system it's easy.. but I assume you have not.
In that case, find the nearest Linux ftp mirror, and look up the
Slackware distribution. Example:

sunsite.unc.edu:/pub/Linux/distributions/slackware

Taking that as the rootdir, you will need the following files:

slakware/a2/ldso.tgz            (for the runtime linker)
slakware/a2/shlibs.tgz          (for libc.so)
slakware/x6/oldlibs/tgz         (for the old X libs that Doom is linked with)

Extract those in /emul/linux, and you're set up, with one possible exception:
you might need to create an /emul/etc/ld.so.cache. To do that, create
an ld.so.conf file in /emul/linux/etc (you only need one line:
/usr/X11R6/lib in it) and run the Linux binary of ldconfig
(it is in the ldso.tgz file, and statically linked). Ignore the error
messages, and mv /etc/ld.so.cache /emul/linux/etc/ld.so.cache.