What is the L64 to L65 promo process?

Hello People,

Just wanted to quickly check with you all to understand what is the L65 promo process looks like? I have been told that one will need at-least 2 peer group Principals to write a document.

1) Does it always have to be a principal from a different team?
2) Can an IC write support for MC? (Of course not a direct IC).

I don't seem to find a proper for L64-65 promo anywhere, people say its the CVP level approval with lot of documentation. How complicated is the promo conversation for Principal promo looks like?