this is one way that will work
1. a place to download and store slackware files and a partition to install to.
2. able to boot from grub.
1. mount the partition you are going to download files to and create directory slackware-13.0 or whatever version you are going to install .
2. extract files from cd's as mentioned before or download slackware/ packages from a slackware mirror to the slackware-13 directory. Alien Bobs rsync script works good for this can get from here: http://www.slackware.com/~alien/tool...are-current.sh
have to modify for mirror you want to use, slackware-version you want and location of the partition to download files to.
3. copy initrd.img from slackware/isolinux and bzImage, System.map.gz from slackware/kernels/hugesmp.s to your boot directory
4. edit your grub menu as follows:
root (location of your boot directory)
kernel /(location of your boot directory)/bzImage
initrd /(location of your boot directory)/initrd.img
5. reboot and select slackinstall and you will be running the same as if running from cd.
6. will have to create a directory to mount the partition to that the installation files are located on before running setup, and give the directory name when setup ask where to install from/