We investigate an ongoing user-driven collaborative knowledge engineering and interaction design process. The anticipated outcomes are knowledge-based support applications for health care professionals and other actors in the dementia domain. The two major goals for the activity in focus are: (1) to accomplish international collaboration across organizational, language and professional boundaries in the modeling of knowledge and design of interaction, and (2) in a local community provide ICT-support for collaboration and communication between organizations, increase knowledge development in individual actors and increase the quality of dementia care. The semantic web-based prototype system ACKTUS is introduced as a tool for modeling and communicating knowledge and interaction, and its role in the process is evaluated. The activity is organized as a part of a collaborative work between different organizations to develop their local clinical practice. Obstacles and success factors when enabling the endusers to design their own tools are detected and discussed.