The right way to do it is to use the original platform (I guess it's evmDM6446 in your case) and do the conversion. Once you have a working converted script, you can start upgrading to another platform.
Can this "upgrading" be done by modifying the generated cfg file in CCS directly? I have noticed that some changes have to be done via the original tcf file in cmd woindow because the associated platform files have to be updated accordingly.
What if the new chip needs a different clock frequency?