Code warrior 5.1 is no longer supported, but you can check if in your nxp web page account you still
have it.
Please login to nxp.com and go to Software & Support then go to Product List

then


then I only have codewarrior 5.2 for HC12, I do not have 5.1, but maybe if you download, maybe you may have it

I hope this will help you