I gather from this that backtrack is a livecd?
You should be able to fix the error message by doing this command in a terminal:
chmod +w /home/man/.kde/share/config/kxkbrc
...but I expect you'll have to do this each time you boot from the CD.
It might be an idea to inform the backtrack people about this one - it's a simple thing for them to fix. From their site, it looks like they're at a beta release of version 2.0, so if you tell them now, the change might make it into the release.