Is it possible to install the PHP library onto an Alfresco instance that was installed using the installer package (alfresco-community-4.0.b-installer-linux-x64.bin)?
If so, how? The instructions aren't very clear, but seem to suggest that Alfresco has to be built from source.
We just spun that PHP library into its own project this week, and it is definitely a work in progress.
That PHP library is an old project that we released as part of Community Edition and which never made it into our Enterprise product. Rather than letting the code wither and die, we have pushed it into Google Code and are encouraging people to play with it. As far as I know it has not been updated for recent releases, and I would not expect it to work with Alfresco without some effort to fix bugs.
The most common way to work with Alfresco from PHP is to run PHP in its own server, and interact using the CMIS API: