I got this tip from a commenter in my previous post about Remote Logoff in Gmail. Sharing it here for those who are still using Internet Explorer 6 or any browsers on which this feature wont work. Gmail checks whether the browser is a compatible one or not and then only displays the link to this feature. But however, if you know the file url , it can be easily used.

Follow these steps:
1) change your browser’s user agent string (you can use something like “Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)”), close the browser and reopen it in order the change to take effect. From now your browser will be identified as IE7
2) Log in to Gmail with your account, et voilà, “Last account activity” is available on the bottom of the page. You click it and the popup opens. Save the url of this page, which will work on all browsers, then undo the changes you made to the user agent string of IE6 and restart the browser.
When you are logged onto Gmail and you need the “Last account activity” page, simply use the url you previously saved.