(1) Paint a patch of the board with a latex paint (very durable).
(2) Sprinkle three of four shades of flock
(3) "Jiggle" the board
(4) Repeat until the board is covered
(5) Tilt the board up and shake off excess flock
(6) Apply a liberal spray of diluted matt medium
(7) Sprinkle a bit more flock on any bare patches
(8) Set aside to dry.
One useful tip is to use a plastic sheet to catch the excess flock and use it for the next board - it's already pre-mixed!
UPDATE: make sure you lightly "wet" the boards before applying the diluted matt medium - see post V for the results if one doesn't.