Since this plugin builds on top of jQueryUI's autocomplete widget, pretty much all of autocomplete's options/events are applies to it as well, with the exception of source.

Google Suggest for jQuery itself has 2 options: service and secure.

Options:

option	type	default	note
service	string	""	It's used to specify what Google service to query against. It can be web, youtube, products, books, news, images, recipes, or "" (empty string). By default it queries Google's web auto suggestions (the web option).
secure	boolean	false	It's used to specify whether to use HTTPS or not. By default it doesn't use secure connection.

Example:

//uses default settings
$("#selector").googleSuggest(); 

//uses HTTPS
$("#selector").googleSuggest({secure: true});

//queries Google Products
$("#selector").googleSuggest({service: "products"});

//alerts the selected value
$("#selector").googleSuggestion({select: function(event, ui){ alert(ui.item.value); }});

You can access the autocomplete settings directly.

$("selector").autocomplete("option", "disable");