CentOS 5.6 - yum update php to 5.2.10

I've had to upgrade my CentOS PHP package to 5.2.10 to enable the JSON extension, but it's not gone 100% smoothly. Naturally..

I used this guide: http://wiki.centos.org/HowTos/PHP_5.1_To_5.2

On completing "yum update", "php -v" showed a bunch of extension errors so I updated those using "pecl upgrade [package]". That reduced the number of warnings down to one:

PHP Warning: Module 'readline' already loaded in Unknown on line 0

I've tried updating this package individually but neither yum or pecl can find it (not installed apparently) despite the readline.so sitting in /usr/lib/php/modules/. I know you need to compile php using -readline, is this now my only option: a complete recompile from fresh?

I hope not.

Anyone able to help? Thanks.

EDIT

5.3 is indeed out and works fine with plesk. To get JSON running had to:

• Update yum with this Plesk / CentOS focused rpm http://www.atomicrocketturtle.com
• Disable plesk sitebuilder functionality (conflict with new PHP version)
• pecl uninstall / reinstall of json package
• double checked it was being called from etc/php.d/
• chmod 755 /usr/lib/php/modules/json.so
• service httpd restart

I know json is included in php-common from 5.2 upwards, but this seemed to fix it regardless. Uninstalling via pecl left it working too.