Currently, many models are used to capture functional software requirements. However, the Software Engineering community has faded interaction requirements into the background, dealing with interface mainly in design time. A sound MDA-compliant software development methodology, called OO-Method, is extended in this work to bridge this gap. The issue is to define a methodology for capturing interaction requirements. For this purpose, the formal notation ConcurTaskTrees (CTT) is used. This notation is a technique that is well-known in the Human Computer Interaction community. A set of interaction patterns has been defined to build CTT models. These patterns are defined with a very precise syntax and semantics. Moreover, transformation rules are defined to transform the Task Model into the OO-Method Presentation Model, which specifies the user interface in an abstract and platform-independent way. However, since editing the CTT models is hard work, this paper proposes superimposing a layer to the CTT diagram in order to capture interaction requirements using sketches. CTT models will be synchronously generated from these sketches. Because this transformation is 'transparent' to the analyst, he only needs to draw the sketches during the interaction requirements elicitation. The approach presented in this paper is instantiated for the environment of the OLIVANOVA technology. This environment makes it possible to obtain a final software product from its corresponding Conceptual Model through a Model Compilation process, where interaction modeling is properly embedded with the most conventional data and process modeling.