OKUMA RENINSHAW programming help

Hi all I come with a desperate need of help. I have a part that is cast. and I need to position the part on an okuma MU-400 5axis. I need to position the part, so I need to level the part on A axis and put it strait on C axis. and also to find the middle of the part. the part is a segment from a big die, and is radial it dose not have straight faces. only radial. I only need to machine some portion only.
Can someone can help me?
Also if you have an idea to take origin when the table is not on C0 A0.

Which control does your MU400 have? Do you even have the Renishaw macros? Or are you probing with the Okuma macros?