def mp_instance_method(args, **kwargs):
    callable_ = getattr(args[1].__class__, args[0])
    return callable_(*args[1:], **kwargs)

if __name__ == '__main__':
    s = "abcdef"
    pool = multiprocessing.Pool()

    args = zip([str.capitalize.__name__] * len(s), s)

    result = pool.map_async(mp_instance_method, args)
    us = result.get()

    pool.close()
    pool.join()