Is it possible to use an AppleScript to set a *custom* paper size in Word?

Question

I've used the following script to set the paper size in Word:
tell application "Microsoft Word"
          set paper size of page setup of section 1 of active document to paper a4
end tell
but I've been unable to write a script to set a custom paper size -- does anyone know if this is possible?
Thanks!

Answer 1

The gallant Pierre strikes again!!!  For reasons having to do with a quirk of working with Word documents coming from a Windows machine, I ended up having to go the UI route, but I couldn't have done it without you!  I actually ended up changing the Format For: popup menu instead of the Paper Size: popup menu, but this technique could be used for those who wish to chose a custom paper size:
tell application "Microsoft Word"
  activate
end tell
tell application "System Events"
          delay 0.5
  keystroke "a" using command down
          tell application process "Microsoft Word"
                    click menu item "Page Setup..." of menu "File" of menu bar item "File" of menu bar 1
  delay 1
  click pop up button 3 of window "Page Setup"
  keystroke "Any"
                    delay 0.5
  keystroke return
                    delay 0.5
  keystroke return
  delay 1
                    click menu item "Print..." of menu "File" of menu bar item "File" of menu bar 1
  delay 1
                    tell menu button "PDF" of window "Print"
  click
                              click menu item "Create Booklet" of menu 1
                    end tell
          end tell
end tell
Again, Pierre -- many thanks!
Andrew