I thought of scaling by multiplying the CIC output with a scale factor, substracting the offset, applying saturation logic at the range boundaries to prevent from arithmetic overflow, stripping the low bits to achieve the intended resolution. You can check the results by pencil and paper method or with a pocket calculator. To achieve an equally spaced output mapping, a higher resolution overhead (2 or 3 bits) is required before the scaling operation. In special cases, the decimation factor can be modified from power of two to an arbitray value. This also provides a scaling option.