Ok, I don't know how you would make a day version of shadowmeld, but I did analyze the fields. You could try modifying the draenei invisibility.
Action duration: The time it takes for the unit to automatically fade when it has no order.
Day/Night duration: Not 100% sure here, but I think it is how long it will last from when the night ends.
Fade duration: The time it takes to fade when the button is clicked.