I think DarkEdge has you covered but for what you need for OBJ2CR2 just follow these steps:-

1. Open UV Mapper Lite
2. File > Load Model
3. Click "OK" or just ignore any initial warning messages.
4. Edit > New UV Map > Planar
5. Planar Mapping > Alignment : Z-Axis, By Orientation > Click "OK"
6. File > Save Model
7. OBJ Export Options ... just go with the defaults.

You will probably need to refine the UV mapping at a later date as your project progresses, but the above will be fine for a run through with OBJ2CR2

Hope that helps.