I have spent a few hours on this and so far I have found the following cemeteries in Bacchus Marsh:
Maddingley Cemetry in Bacchus Marsh
Hopetoun Cemetery, Bacchus Marsh (Roman Catholic)
Holy Trinity Church of England Cemetery in Bacchus Marsh
I have not found any headstones with a reference to the Zulu War so far.
I agree with tasker224. It is time to go back to the person who asked if there were three Zulu War Veterans buried in the cemetery, and see if he/she can provide more information.
Petty Officer Tom