Read an article about doing this, called "Build and Burn." I'd link to it, but I'm not sure if I can post T-nation articles here?
Anyway, to break it down is this:
During your bulk, expect to gain a muscle to fat ratio of 3:1 with a good clean bulk. 3 pounds of muscle for every pound of fat. With that said, after 8 weeks with a 5 pound gain, only 1-2 pounds of it can be fat. This is when you begin a 2 week cutting cycle to strip those 2 pounds off while maintaining the same lean mass gained. Do this off and on and it looks something like this:
8 weeks bulk
2 weeks cut
8 weeks bulk
2 weeks cut
So on and so forth. With this method, it'll take pretty much the same amount of time to reach a desired weight with the same bodyfat you started with as it would for you to dirty bulk then cut down. Why be ripped only after cutting season when you can be ripped all year?

fat slob for half the year, or...
mother****ing machine all year round