I have worked for 20 (of my 40 years in nursing practice) as a CM for insurance companies and service providers and have done w/c for many years in PA, plus - most recently in 5 other jurisdictions. My job with a major insurance company was eliminated in 8/05. I was certified in the second year that the exam was offered. I can say the best way to pass the exam is to do exactly what you are doing. I would recommend that you research the internet sites, CMS and NIH plus Case Mgmt sites for more information.
"The Case Manager's Handbook" by Catherine M. Mullalhy, Aspen Publications, is also an excellent resource. If there is a local chapter of Case Managers near you, perhaps you can contact them and ask if there is a course of study group offered. Sometimes the CM chapter is more hospital-based, but it is worth a try. Good luck! You can do it!!