Advances in educational technology have enabled new forms of organizing and managing collaborative learning environments. One of the currents trends in research on Technology Enhanced Learning is the application of computer-interpretable scenarios, such as those formalized with IMS Learning Design (IMSLD), for the description and deployment of Computer Supported Collaborative Learning (CSCL) scripts. The life-cycle of IMS-LD scripts involves several phases, from the conception to their enactment in actual learning situations. In the context of collaborative learning, group/roles management and composition have special relevance, and are in fact some of the tasks that the teacher must accomplish before students can follow the scripts. This paper presents a software tool (InstanceCollage) that implements a pattern-based approach, which has been previously validated for the task of script design. In this way, it aims at facilitating the population of roles and groups generally described in IMS-LD scripts.