No, the Grey District Council (http://www.greydc.govt.nz/
) does not have any online cemetery information, let alone a cemetery database to search. :-(
Can you get your hands on a set of the NZSG Cemetery microfiche? There are copies around the country in libraries and genealogy groups, and may also be found overseas though I don't know of any specific overseas repositories that hold it.
The cemetery fiche have burial records and monumental inscriptions for cemeteries all over the country, including the closed Karoro Cemetery in Greymouth.
Hope this helps. :-)
Kaiwaka, Northland, New Zealandhttp://freepages.genealogy.rootsweb.com/~wendyh65/