Add attributes ( __attribute__ ) to paramater in c- code

I am using Simulink Coder with a the grt target. When I generate code, I get C-code model.c that contains the following paramater

    /* Exported block parameters */
    real_T myParam = 1.0;           /* Variable: myParam 
                                          * Referenced by: ''
                                          */

what can I provide, using a grt based target and not ert.tlc based target (Embedded Coder) to get the following code.

    /* Exported block parameters */
    real_T myParam  __attribute__((section("CAL_SECTION"))) = 1.0; 
                                        /* Variable: myParam
                                         * Referenced by: ''
                                         */

Add a custom storage class is (so far I know) not an option as it needs the Embedded Coder