Go to www.clamav.net and browse to binaries and ports under downloads

(or use wget to retrieve them.  I used the ones from Petr Kristof)

Download clamav and clamav-devel rpms
vi /var/qmail/supervise/qmail-smtpd/run - comment out qmailqueue and save
run qmailctl stop - then qmailctl stat. 

If qmail-send or others are running kill them
qmailctl start - fresh start without qmail-scanner operating
/etc/init.d/clamav stop
yum update zlib
rpm -e --nodeps clamav-devel
rpm -e --nodeps clamav
(you should see that clamd.conf and freshclam.conf are saved as .rpmsave)
rpm -Uvh clamav-0.84-1.rpm
rpm -Uvh clamav-devel-0.84-1.rpm
mv /etc/clamd.conf /etc/clamd.conf.new
mv /etc/freshclam.conf /etc/freshclam.conf.new
mv /etc/clamd.conf.rpmsave /etc/clamd.conf
mv /etc/freshclam.conf.rpmsave /etc/freshclam.conf
chown -R qscand:qscand /var/lib/clamav
/etc/init.d/clamav/start
/usr/bin/freshclam (make sure it works)
/downloads/qmailrocks/qmail-scanner-1.24/qms-config install
(follow prompts to generate a fresh qmail-scanner-queue.pl file)
setuidgid qscand /var/qmail/bin/qmail-scanner-queue.pl -zg
vi /var/qmail/supervise/qmail-smtpd/run - restore qmailqueue line
qmailctl stop
qmailctl stat (ensure everything stops, if not ... kill it)
qmailct start
some final checks :
tail /var/log/maillog (make sure no errors)
tail /var/spool/qmailscan/qms-events.log (again .. no errors to contend with)
send yourself a test message