You can install Zopim on Google Sites, but note that the position of the widget will be slightly different than it is on other sites, like in the example below:
To add the Zopim widget to Google Sites
- Log into your Google Site in Edit mode.
- Select Insert > More Gadgets.
- Select Add gadget by URL. Enter the following URL in the field:
- Under Set up your gadget, enter your Zopim key, language, and colors.
- Click OK.