Model-Driven Development (MDD) uses models to guide the development of software systems. However, models are usually conceived to be used by software professionals, so it is quite difficult for end-users to understand them because they are not familiar with domain-specific languages or modeling tools as software professionals are. This makes the end-users' involvement within MDD approaches a difficult task. In this paper, we present a method that introduces a set of techniques and tools that allow end-users to participate from early modeling stages in cooperation with software professionals within any MDD approach. To validate the application of the method, we have applied it in a non-intrusive way within an existing MDD approach for developing smart homes.