I've dabbled in it a few months ago using a service from the marketplace. I think it's called topoftheresults.com or something like that, they have a free option for 50 clicks/day.
The good part is that it works. Moved 5 keywords from page 3 to top 5.
The bad part? As soon as it stops, you go back. Maybe not page 3, but you don't keep the flow.
I haven't tried it for a long time, because at that time was afraid of hurting the website. Only used it for 3 weeks.
My theory is that, if your content is good, and you can manage to keep the CTR and dwell time high enough once you reach the higher spot, you can maintain the position. It's just a theory though.