Recent versions of CW for HC08/HC12 (out of my memory, I'm not sure since which version, sorry) have a checkbox in the linker preference which does cause that the compiler preprocessor is first run across the prm file.
If possible, I would stay with a simple prm file, and this means to keep the MY_DATA big enough for the content of all your firmwares so you dont have to do this conditional compilation (or macro replacement).
You can also place the variables with the @ operator (int blubs@x08c
, then those memory ares should not occur in the prm file at all. And in C, preprocessing is possible, of course.
Daniel