Yeah, sometimes the downside to data sheets is information overload.
If you look at the first page, you'll see a figure labeled "typical operating circuit (see figure 5)". Then on page 5, you get another copy of that schematic, along with a section on calculating the values of R1, R2, and R3 for your application.
The problem with measuring battery life is that it isn't a linear function. Voltage drops over time, but the shape of that curve varies with battery chemistry.
-j