There isn't that much difference in hatching chickens and guineas. I often hatch them together. You use the same temperature and humidity for guineas that you would use for chickens. The only difference is that guineas take 28 days and a chicken egg only takes 21 days. With a forced air incubator the temp should be around 99.5. Incubate at between 45 to 55% humidity. After removing them from the turner raise the humidity to between 55 and 65%. Guinea eggs should be taken off of the turner on day 25. It's not uncommon for them to hatch on day 26, 27 or even day 29.
Be prepared for the keets to be really tiny. They can go thru chicken wire easily and they start jumping and trying to fly a lot earlier than chicks. So they need a pretty secure brooder. Another point is that they are not easily tamed like chicks. So don't be surprised if they all pile into a corner whenever you appear. But they are real characters that I really enjoy working with.
Feel free to ask is you need more info.
Edited by red horse ranch - 2/18/16 at 10:17pm