Steps to Install CHKROOTKIT on CentOS:

#cd /usr/local/src

#wget ftp://ftp.pangeia.com.br/pub/seg/pac/chkrootkit.tar.gz

 or

#wget http://www.spenneberg.org/chkrootkit-mirror/files/chkrootkit.tar.gz

#tar -zxvf chkrootkit.tar.gz
#mkdir /usr/local/chkrootkit
#mv /usr/local/src/chkrootkit*/* /usr/local/chkrootkit
#cd /usr/local/chkrootkit
#make sense

Adding CHKROOTKIT to Daily Cron

#vi /etc/cron.daily/chkrootkit.sh

Add this text to the chkrootkit.sh file

#!/bin/sh
(
/usr/local/chkrootkit/chkrootkit
) | /bin/mail -s 'CHROOTKIT Daily Run (PutServerNameHere)' your@email.here

#chmod 700 /etc/cron.daily/chkrootkit.sh