On the This Programming Thing blog there's a recent post showing you how to define your own "sniff" settings for the popular PHP_CodeSniffer tool. The codesniffer lets you define standards that need to be in place for all code in your application and notifies you of violations.
At Zimco, we’ve started working on standardizing our coding but we ran into a little problem while we tried to automate the process of making sure our code adhered to that standard. [...] I think we get into our own way of doing things and everything else is wrong. This code makes me feel irrationally angry (so angry I’m having a hard time not fixing it…). Ultimately, the best way to fix these kinds of formatting problems is to sit down and discuss what’s best and have everyone stick to the same set of standards.
They talk some about the place for PSR in coding standards (specifically PSR-2) and the fact that there's already "sniffs" provided to check against those rules. However, they point out that running this against a non-PSR-2 codebase can be a mess and show you how to customize your own standard to more match your current state. They use an XML configuration file to update the tab width setting to four spaces and then apply the PSR-2 standards. They also show how to exclude certain rules and mention a handy plugin you can use in Sublime Text to keep your code within standards.