Humanoid robots are currently widely studied because of the many future applications they could be used for. Many researchers are working on the locomotion aspects. We are more interested in dual-arm manipulation tasks, because of our long experience on this topic. In this paper, we consider the task consisting in assembling two objects, each of them being held by one of the humanoid arms, as human beings often do. In this framework, we briefly recall methods that we have developed in the past for (i) hybrid position/force control of a two-arm robot and (ii) relative positioning of the end-effectors of two manipulators. We propose to combine these approaches with a solution using the vision system of the humanoid in order to fully automatize the assembly task. Tests have successfully been performed with the OpenHRP simulator of the HRP2 humanoid but they only represent preliminary work. Therefore, this short paper should be considered as an introduction to the research activities we would like to focus on in the future.