How load/save data through ports using custom function/macro?

ERT generated code normally uses global structures for passing data through in/out ports. It is possible to change that with attached signal properties by setting storage class on Code Generation Tab. Options are somewhat limited to three variable based methods.

Is it possible to direct coder to use externally defined function/macro to access data through ports, define custom access method signature/prototype and to specify required header file pre-inclusion on per port basis?

Thanks, Eugene