Fly early, 6a.m. to noon. Lots of routes possible, but I-80 to SLC, then I-15/I-84 to BOI probably keeps the crossing elevations the lowest. I won't go into detail here, there's lots of info available regarding mountain flying, high DA, and leaning procedures, but, basically, learn to use that red knob on your throttle quadrant. Have fun, sounds like a great trip!