Progress,  page 12
One of the great benefits of the foam block system is the ease of making beveled corners.  
Almost any angle can be achieved.  Here we have begun to build the dining room wall, which has
a bay section.  The foam panels are simply cut to the proper angle (see below) and then glued
back together with foam adhesive.  We sometimes used long drywall screws through the foam to
help pin the corners together until the adhesive cured.
Trying to cut angles based on calculations is pretty
futile.  My wife suggested this approach:
a. Mark the outside corner points on the footing.
b. Draw lines through the outside points.
c. Draw parallel lines inside of them at the width
     of the walls (11 inches in our case).
d. Mark the intersection points of the inside lines.
e. Temporarily place the foam blocks on the footing
     and mark the inside and outside corner points.
f. Remove the blocks and cut them at the marks. Be
     sure to make the cuts perpendicular to the run
     of the panels so they will be vertical. It worked
     best for us to cut each side separately.
Here is the result.  Properly bisecting the
angle as described above makes both faces of
the cut the same width and gives a clean
corner.  Since we are putting grout in the
blocks every two courses, the pinned and glued
corner is easily strong enough to hold it.

You can also see some of the wooden shims we
occasionally use to make sure the wall is
vertical.