I'm guessing you need the ME version in CS3 to do that. Is this doc set up for Right-to-left reading?
export your document to IDML and open the IDML file with e.g. Springy (on Mac OS) and a text editor like TextWrangler.
In Springy you can see the IDML file unzipped. Go to "Resources/Preferences.xml", open that in TextWrangler, then search for
and change that to:
save back to Springy, save and close the IDML file.
When opening the IDML in InDesign your document should be right bound.
Sorry. Not possible in CS3. You would need InDesign CS4 and up for doing so.