That's exactly what I was doing back during the spring when I went on an extreme fat loss diet. I was using 120mcg of clen before doing cardio (treadmill at 3.5 mph) for 45 min, 7 days/week, and lost 40 lbs in 3 months. I did the clen for about 4 weeks on 2 weeks off. During the 2 weeks off, I used ephedrine.
Just be sure to start with a low dose, then over the course of several days, work your way up to a dose that gets the heart rate up fast, but is still tolerable. If you start out with a high dose, you will experience terrible shakes, jitters and restlessness that can last for several hours.
KB