how do i install stone veneer over cement board?
Use thin set and stick them right to the c-board. If they are bigger pieces you should screw wire mesh to the cement board for a good bond then tuck point joints After it sets or use a bakers bag.
What kind of stone? Interior or exterior? If interior, what room? Is the stone rough or has it been cut to tiles? Pretty broad question. Please provide more details.
the instructions you get with whatever stone you decide on will explain it in detail...usually mesh with a base coat and then a bonding layer and then the pointing if it is a mortared joint...