You don't need to test hourly. Even when you do a complete curve, every 2 hours is enough. You need to get a number before each shot and then somewhere in the 4-6 range to start with. That will give you an idea of how the insulin is working. Usually with Humulin, the number goes down in that time frame and then rockets back up. (in most cats, Humulin is harsh - hitting fast and not lasting very long. That's why we prefer the milder, longer lasting insulins.)
Once you have the preshot tests and a midcycle number, it will give you an idea of how the insulin is working in your kitty. The other caution is not to shoot under 200, but wait 20 minutes, without feeding. You want to make sure the number is rising and that he is high enough to shoot.