Truecrypt
First, download the device-mapper package for Slackware from:
http://www.linuxpackages.net/search_view.php?by=name&name=device-mapper&ver=10.2
Then use installpkg to install it (as root).
Example:
installpkg device-mapper-1.01.05-i686-1jon.tgz
After that, compile and install truecrypt.
Interesting reading:
http://polishlinux.org/howtos/truecrypt-howto/
page revision: 1, last edited: 04 Jun 2007 01:44