I have a video/training program that I use called "A Bit About Backs"
It is made by CLMI, and my worker's comp carrier gave it to me free. I like it because it illustrates how the back works when lifting quite well. I have found that if you educate your staff on the 'how and whys' of safe lifting practices, its a much easier pill to swallow.
Having worked in the insurance industry for a few years now I can only offer my recolection from a previous job. You can look into the NIOSH lifting equation which can be quite confusing or take a more basic approach. Identify the at risk jobs, then attack the specific issue with engineering controls (i.e. counter balances, suction lift assists, spring loaded lift assists, material roller work tables, ,gravity feeds or possibly different packaging to provide more grip for the lifter). When using engineering controls for material handling its best to work with the operators and get their input. Lastly, administrative controls (i.e. two man lifts, stretching, job rotation, lower quota, etc...).
Back injury reduction can be difficult and expensive.