1) Be sure to change your derivative include file to MC9S12dp512.h, and if using assembly, MC9S12dp512.inc.
2) Be sure to change your PRM file so as to handle the new address ranges.
3) Check your vector.c file to ensure the device interrupts match.
You're going to find out real quick if you've factored your code to hide all hardware dependencies behind symbolics that the header files should automagically correct for you. Good luck.
---Tom