To install Google Earth Plugin using the Google installer, available at http://earth.google.com/plugin/, you need administrator rights on your PC.
For those of us less fortunate, there is hope. Here are the step by step instructions on how to install Google Earth Plugin without admin rights.

This method works for Firefox 3.6. I have not tried it with Internet Explorer, as my company forces me to use IE 6.0, which is incompatible with Google Earth Plugin.
Also, it has been tested only for PCs.

You can do it in two ways, the easy and short one or the easy and long one.

The easy and short one

Download the file GEPlugin_installer.zip from here and unzip it in your desktop. Double clic the file 3c4e82.msi, and the installer will perform the installation of the plugin.
You could probably get an error message about a file called plugin_ax.dll. You can ignore that error, and the plugin will work.

The easy and long one


1. You need to get the files that are installed when the plugin is installed. To do this, install the plugin in another computer and copy the files.

2. You need to get:

- All the files and folders in the path #USER#\Application Data\Google\Google Earth\Plugin

- The file 3c4e82.msi
This is the installer that will do the trick.

Use the search function in Windows to find those files.

3. Create a folder in your desktop, and put the 3c4e82.msi file there. Inside that same folder, create the full path
\program files\Google\Google Earth\plugin
and copy the contents of the plugin folder of the previous installation.

4. Double click the 3c4e82.msi file. You will most probably get an error message about a file called plugin_ax.dll. You can safely ignore that message.
If you get more messages about missing files, check that the path you have created is correct.

5. And that's it! Launch Firefox, go to maps.google.com and click on 'Earth View' to see that the plugin is working.