CentOS6.4 x64 install Percona 5.5 using yum

$ service mysqld stop
$ yum remove mysql
$ rpm -Uhv http://www.percona.com/downloads/percona-release/percona-release-0.0-1.x86_64.rpm
$ yum install Percona-Server-client-55 Percona-Server-server-55
$ service mysql start

reference
http://www.percona.com/doc/percona-server/5.5/installation/yum_repo.html