How to port touchwiz roms. Help topic

Hey i want to port a touchwiz ROM and i don't know how to. So any guides to show how touchwiz roms are ported.

I really want to port Samsung's android 5 leak rom to s3. There so many Dev's out there that port S5 and NOTE 4 roms to s3,s4,note2 and
note 3.






THANKS