Hardware accelerators are widely adopted to speed up computationally onerous applications. However their design is not trivial, especially if multiple applications/kernels need to be served. To this aim the Multi-Dataflow Composer (MDC) tool can be adopted to generate the internal computing core of flexible and reconfigurable hardware accelerators. Nevertheless, MDC is not able, as it is, to deploy ready to use accelerators. To address this lack, we conceived a fully automated design flow for coarse-grained reconfigurable and memory-mapped hardware accelerators, which required: a) the definition of a generic co-processing template, the Template Interface Layer; b) the extension of the MDC tool to characterize such a template and deploy the accelerators. This methodology represents, within MPEG Reconfigurable Video Coding studies, the first framework for the automatic generation of reconfigurable hardware accelerators and, as it will be discussed, it may be beneficial also in other contexts of execution with fairly limited adjustments. Results validated the proposed approach in a real use case scenario, comparing the automatically generated co-processor with a previous custom one.