I'm trying to find any recommended tools for XSS security testing using OSX. I tried using the latest OWASP Xenotix XSS Exploit Framework 4, although when used via CrossOver it crashes upon trying to use the Scanner :/
In order to test only for Cross-Site Scripting, your best bet is to find a good intercepting proxy that will allow both manual and automatic tests. Burp Suite is a perfect example and can be executed on OS X, but keep in mind that the free version is pretty slow when using the Intruder for automated attacks.
The reason to perform also manual tests is that you'll need to check exactly how and where the payloads are placed inside the response, something an automatic scanner can't do.
To complete your toolbox for XSS testing, get a good cheat sheet and you should be able to succesfully assess your application. Keep in mind that XSS research is ever-expanding and you'll probably want to keep up to date with the latest discoveries (eg. sla.ckers.org has a section specific for XSS).