Hi,
When I have been using simmular things in the past, to trace them out, I use a battery such as a 9V one and a resistor, but in this instance I would not reccomend using this approch, I would in this instance use a AAA battery so that you can be fine with the (logical) voltage levels.
Now in order to test the displays (I do this with 16 segment / 7 segment displays) I pic one of the "pins" as a ground and run the positive across the other pins and make note of the result.
If you get a segment flash, this is a good sign it means you have the ground right (most of the time).
If you get nothing, it could be one of two things, 1st is that you havent got the ground / power right (most common), or the didplay is fried, not often the case, deffinately if you do it quick.
Once you have these you can drive the display as you want.