Get the existing counter dull by going over it with a power belt sander. Use the sander just enough to remove the shine from the surface.
Measure across the length of the counter and mark the center. Use a square to draw a line front to back at the middle.
Spread tile adhesive over the whole counter surface with a notched trowel.
Press trim tiles onto the counter surface at the front edge, starting at the center line and building your way to the sides. Keep the finished edges lined up on the edge of the counter. Put spacers between them as you go. Cut the last tiles on both ends to fit as needed, using your tile cutter.
Press regular tiles in a course behind the trim tiles, starting at the center line and building to the sides. Put spacers between them. Cut the tiles at the ends as needed.
Press more courses of tiles into place, starting each at the middle and working your way back. Cut the end tiles as needed. Cover the entire surface.
Let the adhesive set for 12 hours. Pull out the spacers.
Spread grout over the surface with a grout float, pressing it into the spaces between the tiles. Use a damp sponge to wipe up the excess grout.