I just installed EndNote X4 on my Mac. The EndNote CWYW Word 2008.bundle is in the startup folder for this version of Word. However, when I try to open the file, I get the message “EndNote CWYW Word 2008.bundle uses a file type that is blocked from opening in this version. To help secure your computer, some file types are blocked from opening when you double-click the file or drag the file to the Microsoft Word icon. If you trust that this file is secure, you can open the file by clicking Open on the File menu. Learn more about blocked file types.” From word, I cannot open the file. As a result, the EndNote tools do not appear in Word. When I open Word or a document, I get the message "Word could not load this add-in program. (EndNote CWYW Word 2008.bundle).
You probably did this, but if not, re-boot your computer. If the problem persists, try repairing disk permissions. To do that, go to the Utilities folder and launch Disk Utility. In the left pane, click on your hard disk. In the right pane, click on the First Aid tab and near the bottom of that window, click the button “Repair Disk Permissions.”