in this case treat them like linebackers lotts of contact drills and make it a compition to see who makes the best tackels.allways remind them that they are the only contain guys and stress the importance of that.

first for the out side contain. Outside hip(fanny cheek) needs to be parelell to the sideline. The next piece, make sure that at the snap the are taken a back/read step, once they have read run. Have them foot replace forward and explain how and why. Then offer something for perfection on that part. once that starts to happen, the tackles will come as powerful and concise parts of their play. Make a point of single out the coners who have plays run away from their side. you will have productive corners in no time at all.

First step, is to have corners take read steps. Generally done in good
break down position pad level down and controled back peddle. If no
receiver is over him he is to come up in force in 9 technic. (what is this??)
9 technic is outside shoulder free and force is driving up field. in our defensive
scheme we want only two options for the running back .1-be tackled by the
corner or 2nd option is the cb turns the play in were we have percuit
from inside defenders.

I am more of an offensive guy and I don't know how it is in your league but in the league I coach in very rarely do the teams we play have wide-outs. If not teach them to play like linebackers and attack the football. If they do have a wide-out lined up on them we teach our guys just to contain and force the play inside so a linebacker can clean up.