How to add GoogleBot as user agent in it?
In firefox tools menu, select user agent switcher->options and add this user agent:
Googlebot/2.1 (+
http://www.google.com/bot.html)
Manually Install a Firefox Extension
To manually install a Firefox extension into Firefox, download the add-on to your computer. If the download option isn't available, right click on the extension install link and select "Save Link As..". Be sure not to change the file extension. A Firefox extension will usually be a .XPI file.
Next, go to the Firefox drop down menus at the top of the browser. Select File > Open File then select the addon.xpi file and click on Open. The Software Installation window will appear, click install, restart Firefox.
Alternative Method
Go to the Firefox drop down menus at the top of the browser. Select Tools then Add-ons. Minimize Firefox so that only the Add-ons manager window is showing and drag the addon.xpi file onto the Add-ons window. The Software Installation window will appear, click install, restart Firefox.