Clean stairs of all debris using a broom.
Lay out several of your tiles in a row, using the spacers to evenly space the tiles.
Measure the distance of the span from wall to wall. Find the center point, and check your measurements against the tile you laid out on the floor. If you can start with a full tile in the center and have a nice-sized cut on either side, it will be fine. If the cut is too small (2 inches or smaller), you can adjust the center point to one side or the other to compensate.
Using your grease pencil, mark the center of each stair so that you have a starting point as you work your way up (or down, depending on preference)
Double-check your measurements and re-sweep to insure that no debris is on the surface.
Following the instructions on the package, mix the latex thinset mortar using the drill and beater.
Measure the vertical part of the stairs with your tape measure, and if necessary, mark the surface of the tile with your grease pencil. Then use your cutting board to cut the vertical pieces to fit. To have the best view when coming up the stairs, you will want to set the vertical parts of each step first and cut the horizontal pieces to fit.
Check the size of the vertical cut against each vertical section of the stairs. Chances are they will be fairly similar and you can simply count out how many pieces you need to cut, set the gauge on your cutting board and make as many as you need. If there is too much variation in each stair, you will need to cut each piece separately.
Using your 3/8-inch trowel, spread the thinset evenly on the surface of the vertical section, leaving your center mark slightly visible. Take your tile and place it where it needs to go and apply pressure, moving slightly side to side until you hear air escaping. This means a full bond has been created and all the air forced out. Use your tile spacers between the tiles to ensure proper spacing and grout joint size.
Repeat Step 4 on the next vertical section. Then, measure the distance from the face of the first vertical piece to the face of the step up (or down, whichever way you are working) across the horizontal step. Mark the size of the cut on the face of a tile with the grease pencil and use your cutting board to cut it to fit. Work your way to either side, and use your tape measure and cutting board to make the cuts on the end as well. Use your 3/8-inch trowel as in Step 4, applying thinset evenly and using pressure to insure a proper bond between the tile and the stair surface.
Repeat Steps 4 and 5 until you are completed. Let dry for 24 hours before grouting.
Using your margin trowel, mix the grout in a bucket according to the instructions on the package.
Using your grout float, force the grout into the joints between the tiles. Wipe the excess grout from the surface by pulling your grout float at a 45-degree angle across the grout joints. Do not pull with or against the joints, as you will pull the grout out. Work diagonally.
Let dry for 15 to 20 minutes. Check the solidity of the grout by tapping it gently with your finger. If it sticks to your finger, it is too wet to clean. If it does not stick, you can continue.
Using a bucket of water, wring your sponge out until it is slightly damp. Using circular motions, work the excess grout into the grout joints and smooth them, using only slight pressure.
Wait 15 to 20 minutes, then clean the remaining haze from the surface by using a damp sponge to pull diagonally across the grout joints. Wring your sponge out frequently.
Let dry for 24 to 48 hours before allowing traffic.