Howto install imagemagick and PHP imagick extension on Linux CentOS 5 LAMP server. It is pretty simple really

yum install ImageMagick.i386
yum install ImageMagick-devel.i386
pecl install imagick

After the installation, create an inclusion file in your /etc/php.d directory for imagick.so module and then restart apache daemon:

echo "extension=imagick.so" > /etc/php.d/imagick.ini
/etc/init.d/httpd restart

Test the loading of the module by running:

php -m | grep imagick