Stu, You are correct, the OCC Handbook series are a good resource. Even though we are a National Bank with the OCC as our primary regulator, I also frequently refer to the FDIC and OTS Handbooks as well. They all have good information in them, each with a little different perspective.
Another resource is the Fiduciary and Investment Risk Management Association (aka FIRMA). This organization specializes in fiduciary/brokerage/investment adviser audit, compliance, and risk management activities. Their web address is: www.thefirma.org
MBG is a regular speaker at the annual conference and has been instrumental in in the development of the website.
The American Bankers Association has a Trust Section headed by Sara (Sally) Miller that is a great resource. The ABA's web address is: www.aba.com
An finally, if actual training is what you are looking for, the Cannon Financial Institute has a terrific certification program for trust audit and compliance professionals. Their web address is: www.cannonfinancial.com