Use the following widgets on your research guides or other Library pages:
EBSCO Search Box Builder
You can select the databases you want this widget to search, provide limiters and create a custom name for the widget here:
http://support.ebscohost.com/eit/searchboxbuilder/
Choose IP address as the authentication method.
Gale Database Widget
http://access.gale.com/databases/
Proquest Search Widget
http://www.proquest.com/en-US/utilities/widgets/index.shtml
Credo Reference Widget
Link: Admin only
JSTOR
http://www.jstor.org/page/info/resources/librarians/searchWidget.jsp
Knovel