Mark the location of the walkway with spray paint or string. Dig down approximately eight inches for the entire area of your path. Allow four inches for the crushed stone, two or three inches for the sand and then the thickness of your stones.
Pour the crushed stone into the hole. Make sure it is relatively level and compact it with a hand tamper or plate compactor.
Construct a form with one-by lumber along the side of the crushed stone. Pour sand into the hole and level using a screed. The sand should be high enough so that when a stone is placed onto the top of the stone it will be level with the form and the rest of the yard. A screed can be made by notching a piece of wood.
Start laying your stone. The stone should be out of level about 1/8-of-an-inch for every foot wide the path is. This will allow water to run off the path. Leave about a half-inch space between each stone. Cut the stones as necessary with the masonry blade in your circular saw. Continue laying the slate until the path is completed.
Grout the slate by shoveling sand or stone dust on top of the completed path. Sweep the sand or stone with broom so it fills in the gaps between the slate.
Compact the sand into the joints with a mason's trowel then sweep off the excess sand.
Remove the forms, and then back-fill up to edge of the path with dirt.