This article suggests that Lime is usually coppiced on a 25-30 year rotation although I imagine that could be coppiced at a more frequent interval and still product leaves.
Coppicing is a simple process, especially if the tree is relatively small. Once the tree has reached the desired size/age, cut the stem/s low to the ground (1-2") while the tree is dormant. From the following spring the tree will produce multiple shoots. These may need protecting from grazing animals and livestock.
There's a loads of books on coppicing and a fair amount of info on Youtube. Ben Law has written some excellent books on the subject and is a professional coppice worker himself.