Applications can add items to the Weceem "Administration" page but using the Navigation plugin that Weceem CMS uses, to add items to the navigation group "weceem.app.admin". For full details see the documentation for the Navigation plugin, but the Weceem Application does this:
class UserController {
def authenticateService
static navigation = [group: 'weceem.app.admin', action: 'list', title: 'users']
}
The navigation plugin uses this convention property to place the "list" action of the user controller into the "Administration" section of Weceem Admin.