We encountered some issues using the PHP CodeSniffer plugin. We found that the rules.xml file is not encoded in UTF-8 and then raises an error when it's parsed by CodeSniffer. We had to manually encode it into UTF-8 and then re-inject it in the jar.
It seems also that the stax2 lib is used by the plugin but is not available inside the Sonar classpath. After making it available to the plugin, everything works fine.
We really appreciate the effort you're doing on these tools.
Right now, we're installing a SONAR PHP platform in order to test. We'll let you know how it goes.
If we can help in any way, feel free to contact us.
LOGICA Software Quality Center
(We speak French and English)