How does the MEO class 4 exams work for offshore vessel seafarers?

Planning to join Boskalis(offshore vessels) for my first engine cadetship. I'm currently with anglo eastern and Boskalis uses their recruitment services. How would the class 4 exams be, when I appear for them after my seatime? What can I expect, would it have additional papers, would there be any change in syllabus? How would the difficulty of the orals compare to that of cadets from main fleet? Please share your experiences, even deck officers!