A download of all installed PHP 5.2.17 packages and yum localinstall php* brought up libt1.so.5 dependancy problems that I could not fix....BUT,
A little more googling found this, which resolves all dependecies and works bl00dy perfectly!
yum update php* --exclude=php*5.3*
...basically, update all the installed php packages to the LATEST, EXCEPT PHP 5.3 packages.
It will give you a full list(scroll back up) of what it found, and intends to update, before you hit Y.
There were also no moans or groans(errors or dependencies etc) from yum.
The older PHP packages are obviously still there, just yum tries to install the latest(5.3.x) by default.I hope it helps all those who DO NOT WANT PHP 5.3.x!iiimriii,
I am using Plesk 9.5.3 with PHP 5.1.6(now updated to PHP 5.2.17) on CentoS 5.5 x86_64...and everything seems to work including Plesk and all my Joomla and Vtiger installations.