[plt-scheme] SLaTeX figures

I am trying to make a figure displaying some Scheme code with a box around it, 
ie something like this:

    \begin{figure}
    \framebox{
      \begin{schemedisplay}
      ...
      \end{schemedisplay}
    }
    \end{figure}

Which does not work.  Neither does this:

    \begin{figure}
    \begin{schemeregion}
    \framebox{
      \begin{schemedisplay}
      ...
      \end{schemedisplay}
    }
    \end{schemeregion}
    \end{figure}

I've tried other variations, but I can't seem to make this work.  Does someone 
have any insights into how I can typeset the above?

Thanks,
David

PS I've known SLaTeX to be a great program for some time now, but it's worth 
reiterating.  SLaTeX is a great program.