Dear tgpitts,
You're right to be sensitive to the BIA. It is the foundation for planning and the core of business but it's also the most complicated component of the BCP. The BIA actually identifies how you are creating value (the core of doing business every day) and, if done well, chains any crisis back to that creation of value. It also pulls the entire BC Management program together (planning, prioritization or response, training, testing, etc) so it's well worth your time to get some training or even invest in the process and hire a pro to design it for you while training your team at the same time.
The biggest problem you're going to face in reaching out is a deficit of information that you can actually apply without intense frustration. There's a good book: BSI's A Practical Approach to Business Impact Analysis <
http://shop.bsigroup.com/en/ProductDetail/?pid=000000000030235851> I'd recommend getting a mentor as well.
CHeers - Eryn