When I use the keypoints saving algorithm is it possible to set keypoints manually (or choose the area in which I want my points)?
(I need specific keypoints to use the keypoints matching algorithm to recognize a small object)

Ibrahim has to answer this. I haven’t touched that code in a long, long, long time.

No you have to save the descriptor first and then edit with the keypoints editor in the IDE:

Tools->Machine Vision → Keypoints editor