If you don't need a quick release you could most defineatly keep it, it would look wierd but it wouldn't be hard.
You could make something but I can't picture it being easy to use. If you used the stock parts, it would be ugly and take up a good amount of space. It would be kind of hard to use, depending on where you put it. I think a small on/off switch a toggle like switch that arn't on and off, that you could push up and down to adjust speed would be the smallest and easiest. I have never looked at the wiring but you can always redo what the factory did with different parts, it just may be hard to find what you are looking for.
One thing to take into account, if you do get it to work it will be ugly and/or hard to use but also lower the resale value of your car quite a bit. I wouldn't mind if someone ditched cruise control all together but wouldn't touch something with hacked wiring. I am not the only one.