In Markbook, these are referred to as "Staff Roles".

Important to note
This requires Administration access to Sentral Markbook.
Staff assigned Teaching Access will appear on printed reports for this class.

To assign Staff Roles
In Sentral Markbook, go to Markbook Setup.
Click on Staff Roles.
Click on the relevant staff member/teacher in the left column
Click on the Markbook you want to grant access to in the right column, and then select the class they teach/require access to.

This will assign that staff member to the class, and therefor the Markbook.