[OS X TeX] Memoir --- Two columns for exercise sets

[David Arnold]

All,

I am using the memoir class, and thanks to Ross, I can now typeset  
some exercises.

I am using:

\chapterstyle{bianchi}

which provides ample margin space on odd and even pages.

To typeset the exercise sets, I'd like to switch to two column format  
and lose the extra magin space to gain more space for the exercise  
sets. Once the exercise sets are completed, I'd like to jump back to  
the bianchi style.

How do I do this?

Thanks.

D.