The current phpMyAdmin and php-ioncube-loader packages from Atomic won't install on a server using the EL5 php53* packages, because they have dependencies on 'php', while the php53 package only provides 'config(php53)', 'libphp5.so', 'mod_php' and 'php53'. Could the Atomic PHP-related packages be modified to also work with the EL5 php53* packages?

why would you install the php53 packages? those are obsoleted by the newer php 5.3.8 series

Some clients prefer to stick with the CentOS packages, since they are maintained for a longer time. If you're using the Atomic PHP packages and Atomic goes to PHP 5.4 or higher, they have to as well, which is usually not very convenient.

Im not sure what you're asking for here then

I'd like to be able to use packages like phpMyAdmin, php-ioncube-loader and php-zend-guard-loader from Atomic with the EL5 php53* packages from CentOS. I'm sure they are compatible as they work when I install them using rpm with the --nodeps flag, but if the dependency on 'php' could be changed to to something provided by both the php and php53 packages, like 'libphp5.so' or 'mod_php', then the packages I mentioned would also cleanly install via yum on servers using the EL5 php53* packages.

I guess alternatively I could create a dummy compatibility packages which provides the required php* dependencies and requires their php53* counterparts.

Yeah its probably better to do those yourself, maintaining parallels implementation logic like that is a lot of extra overhead.

Ok, I built those and it's working.