Is it permissible to enroll in school while in B-1/B-2 status?
No, it is not. The regulations, at 8 CFR 214.2(b)(7), specifically prohibit study in the United States while in B-1 or B-2 status.
Before enrolling in classes, individuals who are in B-1 or B-2 status must first acquire F-1 (academic student) or M-1 (vocational student) status. Enrolling in classes while in B-1/B-2 status will result in a status violation. Individuals in B-1 or B-2 status, who have violated their nonimmigrant status by enrolling in classes, are not eligible to extend their B status or change to F-1 or M-1 status. These regulations provide no exceptions.
http://www.uscis.gov/working-united-states/students-and-exchange-visitors/students-and-employment/special-instructions-b-1b-2-visitors-who-want-enroll-school
All Non-Immigrant Visa’s are regulated by the U.S. Dept. of Homeland Security (DHS)