I`ve worked on a slackware installer called nemonico that facilitates the hassle of preparing
the disks for layering LUKS / MD / LVM in almost any order. If you wish to install Slackware 12.0-12.1 with this features it would not be a waste of time if you try and download nemonico from http://sourceforge.net/projects/nemonico
Its not a distro, its just an installer for Slackware and the tools ( nemo.* ) to coexist with.
If any suggestions please let me know trough the forums.