Transverse-to-longitudinal phase-space-exchange techniques have opened new possibilities towards shaping the temporal distribution of electron beams. Sub-ps bunch trains have been experimentally realized at the A0 pho-toinjector at Fermilab. Recently, the combination of such emittance-exchange methods with nanocathode arrays was suggested as the backbone of compact coherent short-wavelength sources. In this paper, we discuss a possible proof-of-principle experiment to produce coherent optical transition radiation using a ∼ 4 MeV electron bunch. The optically-modulated bunch is produced from a structured cathode combined with a transverse-to-longitudinal phase space exchanger.