Before you import the page you have to set the import option, to place the page # you want. I don't think you can change the placed page after it's been placed on the page.
Thanks. I figured it out. I was talking to the document instead of the application. That's always tricky for me.
tell application "Adobe InDesign CS3"
set TheFilepath to ""
set page number of imported page attributes to 2--or whatever page
place "TheFilepath" on page item "box1" of active document