To use IL with CAL, you will need to do some set up and mapping, as Micah explained. The CAL samples in the SDK show examples of that.
And you can go from Brook+ to IL easily. The issue is that brcc output IL is not compact, so the mapping in CAL can get murky, and I would not go that route now.
But we are working on cleaing up the brcc output IL for the next release -- am hoping that will help.