Converting Pages to Grayscale

Hello,

I was wondering if there is a way to convert only some pages of a document to grayscale and not all of them in Acrobat 9 Pro.  Right now I'm creating page spreads separately, converting each one individually and then combining the color ones with the grayscale ones into one final document.  It would be easier to create the whole document in Quark, save it as one pdf and then convert the particular pages to grayscale in one document.  It would be much faster.  Is there a way to do this?  Thank you.