Not sure what you mean. You mean LFS with Slack as a host distro or... well, whatever the hell I just did.
I built one LFS with Slack as a host distro, just following the book for the most part except for substituting lilo and bsd-inits and so on. But this was awhile ago on a 2.4 kernel. No problems. Slack's a pretty ideal environment. Then, just now, I kept one eye on an LFS book - some testing/unstable/cvs something and one eye on the Slackware source tree and my third eye on my own ideas and seem to have constructed a kind of Pslack, or pseudo-Slack. It's definitely *not* Slackware and definitely *not* LFS. I dunno what it is, but I think I like it. Only problem I had there that wasn't of my own doing was that my module-init-tools segfaulted on booting into my system. Turns out to be high irony - if you do 'make check' or 'make tests' to make sure that your module-init-tools *work*, that makes sure they're *broken*. You may be able to run 'make clean' between 'make check' and 'make install' or do what I did and skip the check on a recompile and reinstall. Now they work. This was under 2.6 and I haven't noticed anything else to watch out for.