Disclaimer, this is generic advice, not tested on Knoppix as I am currently downloading it.

As a first step you should look at the manual page for hwclock. It has facilities to account for clock drift, and is probably already installed.

I like Dan Bernsteins 'clockspeed' package. Essentially have to download the source and compile it. You then give it an accurate time using NTP, wait a while, give it a second accurate time using NTP. It then uses this to work out how much it has to adjust your clock by, and then sits in the background doing so.

Available from http://cr.yp.to

Warnings. Dan's stuff is not "Open Source". You get the source code from him, and can do anything you like with it except redistribute it. I have no problem with this, but some people do.

It uses the high resolution clock cycle counter on your machine, so if your machine changes its clock rate, then 'clockspeed' will not work for you.

You can write a tiny shell script which calls adjtimex in an infinite loop, or failing that you can always write a small C (or whatever) program, which calls 'adjtime', then sleeps in an infinite loop.