If Disability Services (DS) has received documentation of a disability that warrants test accommodations, DS will state that whatever the student and the professor arrange is fine, as long as it is fair to both the student and the professor. This information is included in your accommodation letter that you give the professor. Alternative test administration should be grounded in institutional standards of fairness and security. The key is that the test should be a reflection of the student's ability rather than disability.
No explanation/interpretation of vocabulary or test questions is permitted beyond that which the entire class would receive. DS will also inform the professor that the Learning Center can facilitate the test accommodations if needed. It is the responsibility of the student and the professor to make the arrangements with the Learning Center staff.