As an afterthought, what I would recommend, is taking a look at Zeppoo(zeppoo.net). FYI, zeppoo is 2.6 only.
From the docs:
"Zeppoo allows you to detect rootkits on the i386
architecture under Linux by using /dev/kmem and
/dev/mem. It can also detect hidden tasks,
modules, syscalls, some corrupted symbols, and
hidden connections. Anti-Rootkits which don't use
these methods can be fooled easily."
Also of interest,
Bypassing Chkrootkit(translated):
http://translate.google.com/translate?u=http%3A%2F%2Fwww.zeppoo.net%2Farticles%2FBypasserChkrootkit&langpair=fr%7Cen&hl=en&ie=UTF-8&oe=UTF-8&prev=%2Flanguage_tools