You can lay Slate paving in the same why you would install any natural stone or porcelain paving products. Basically they should be laid on a full wet bed of mortar over a compacted hardcore base, deep enough for the site conditions. For further reading please follow the link to our tech guide:
We would additionally always recommend using a slurry primer when installing slate paving to help bond the slabs and the sub-base together. This will result in a greatly improved installation.