Carton serialization by carton type?

We are beginning setup to provide carton serialization to a major global corporation.  They want their SSCC numbers to vary based upon carton type (inner cartons get a prefix that differs from a mixed- or single-item pallet).  We cannot find a way to use standard E1 to accomplish this - we can only generate an SSCC number with a single format because the carton type is not passed into the "GenerateSSCCNumber" business function that we have created.  Are there any ways to do this with standard E1, or are we doomed to a customization to P4620 and B4600960 and possibly