well I used some 1 x 1 bricks withe the stud on the side and a hole on the opposite side. to those you attach a normal 1 x 1 and it is equal to two bricks sideways.
If this explanation was hard to understand and it is,
here are some helping pics.
If you guys still don't get it then open up the Ldraw...
I would have shown you guys some pictures but,
1. I didn't have pictures.
2. I only have black extra pieces and the pictures would look horrible
so LDraw it is
And yes I have built it and it does work,
Each slope is attached to the 3 thick wall by two studs in the middle row of studs of the wall.
hope it now makes more sense...