by WarheadsSE » Wed May 23, 2012 12:44 pm
Typo from memory on my part with the path, sorry.
pacman -U can be used for installing specific, non-repository packages and/or packages from your cache. However, if you have not previously installed 5.3, then it's not going to be available in your cache.
I believe that PHP comes unmodified from upstream, so you could go back versions and recompile with makepkg to get that version.