Try these sites:http://nyrgs.org/cemeteryRecords/index1.htm
"Please contact us to learn more about the interment options available at Mount Hope Cemetery. Call us at (585) 428-7999, or fill out our contact form and our cemetery staff will be in touch with you. 1133 Mount Hope Ave. Rochester, NY 14620"
Like many government office they have been downsized, but these should be someone there during normal business hours. Call ahead to see what the staffing will be. No idea if they will place a marker, but the actual burial spot is given in the digitized records.