The United Nations Office on Drugs and Crime has released several large new documents on drug dependence treatment, including:

Community Based Treatment (http://www.unodc.org/docs/treatment/CBTS_AB_24_01_09_accepted.pdf)
Drug Dependence Treatment: Interventions for Drug Users in Prison (http://www.unodc.org/docs/treatment/111_PRISON.pdf)
Drug Dependence Treatment: Role in the Prevention and Care of HIV and AIDS (http://www.unodc.org/docs/treatment/111_HIV.pdf)
Sustained Recovery Management (http://www.unodc.org/docs/treatment/111SUSTAINED_RECOVERY_MANAGEMENT.pdf)

MI is discussed in each of them.