Linux Malware Detect (http://www.rfxn.com/projects/linux-malware-detect/) installation is quite easy :).
download via the link, http://www.rfxn.com/downloads/maldetect-current.tar.gz.
Unzip the file # tar zxvf maldetect-current.tar.gz
change the directory to extracted one.
which will install the scanner to your system. To perform the scanning itself you are to run
Eg: maldet -a /var/www/html
-a option here means that you want ro scan all the files.
Use -r instead to scan only recent ones.
Yout will get an scanned report in screen, use maldet -q to view the reports.