Cetnos 32 bit için

wget -q -O – http://www.atomicorp.com/installers/atomic.sh | sh
yum install php-mcrypt.i386
yum install libmcrypt.i386
service httpd restart

Centos 64 bit için

wget -q -O – http://www.atomicorp.com/installers/atomic.sh | sh
yum install php-mcrypt.x86_64
yum install libmcrypt.x86_64
service httpd restart