I'll respond.. First of of all.. I will point out that most on this site will tell you to choose one or the other.. CC or LS... and not to mix the two.
I am hard headed myself and I mixed the two. I like my setup but afterwards I wished I would of went with sand-only.. mainly because it makes everything look "smoother."
if you want to mix the two.. I would remove any rock you have for a few moments.. and put any fish you might have in some large bags and leave them hanging in the tank while you add the sand. after the sand settles give it about an hour and release the fish.
Good luck. btw.. I would go with sand only, I really like the look of sand by its self