Game Coding

I would like a freelancer who has good knowledge of coding games, knowing how the game works. I would like to add in a function within a PlayStation game that would call a custom menu, I believe this would require C++, ASM, GSC although I’m not fully sure. I have necessary documents etc which maybe needed and as well possible addresses to write the menu to. Believe this needs writing to memory of the eboot and possibly writing to a fast file too.