I have close to the same setup
and you should use the ASIO driver to drive the Firepod/Sonar interface. Make sure your hz/bit rates are set the same in the Firepod control panel and Sonar. Shut down and then restart your computer and then Sonar.
Then, each audio track should give you the option of assigning on of the Firepod's inputs and/or outputs. Just remember that even though you have 8 preamps on the Firepod, there are only 4 stereo busses...that's why you'll see Firepod 1L, 3L, 5L, 7L as available output busses. You'll need to use your pan control to get a good pass-through (if you're using the 1/4 inch outputs into a mixer for live sound while you record. Example - audio track 6 should have input as "Firepod - input 5R (notice the "right") - output 5R - then pan the track completely to the right.
Hope this makes sense.
Jay