Firefox 3 Beta is great but still not compatible with some existing Add-ons. But, if you still wanna try Firefox 3 Beta, here is another solution. MultiFireFox for Mac OS X can run Firefox 3 Beta without destroying the old profiles of Firefox 2 that is already installed. To run it, you need to follow the steps after the break.

Step 1. Download the DMG file here.

Step 2. Drag both Firefox 3 and MultiFirefox to Applications.

Step 3. Close any Firefox that is running. Run MultiFirefox, and it will warn you to create one more profile.

Step 4. Enter the name you want to create it. E.g. “firefox 3″

Step 5.  Run the MultiFirefox from Applications again, choose “firefox3″ under profile, and “Firefox 3″ under version of firefox.

[via dangerouslyawesome]