Add custom groups in the quicklaunch of the site

Objective is to add the custom created group in the quick launch of the site.I tried to explore the web and site object to get the handle of the people and group quick launch,but directoly it does not exposes anything..then i get this property to access the quicklaunch..

Here is the code sample..

site.AllProperties["vti_associategroups"] += ";" + oGroup.ID;
add custom group in the quicklaunch collection in the following way..

happy coding..