Projector-camera (ProCam) systems have a potential to become popular and affordable as they can create interactive surfaces for example on tabletops, walls, household items or on a palm of a hand. The possibility that these systems will be used at homes in the future is increasing. The elderly living alone at home often need assistance in their daily tasks as the likelihood of cognitive and motor skill related impairments increases with age. ProCam systems could be used for guidance due to easy to manipulate large interaction surfaces, but research on its suitability for elderly users is scarce. Our research focus is on elderly users and examining their characteristics as potential users of ProCam systems and the implications for interaction design. We conducted a user study with a mixed impairments group of elderly aged 82-94 to investigate how a personalized and skill-suited user interface should be designed. In our qualitative approach, we discovered that the combinations of both cognitive and motor skill deficiencies of the elderly prohibit one-for-all designs so the user interface design should be adapted to each individual's interaction skills. Lastly, we make suggestions for designing ProCam interaction for elderly.