So I now have a Bond library catalogue search gadget to add to my personalised Google page. In the near future it will have to move to a more official home, and may be fancied up somewhat.
If you want one for your library system, the easiest way will be to find a gadget that looks similar to what you need and then adapt to suit the url search syntax for your system. Some html, xml and javascript expertise will be a help.
UWA Library has one available with tabs for different search strategies. Thanks Kathryn for your post - if I hadn't read that I wouldn't have been fiddling with gadgets on a Friday evening.