common image scaling properties

Is there any way to set a common set of image scaling properties for print output, without editing every instance of the imagedata element?

I want to set:

scalefit="1", width="100%", and contentdepth="100%"

as per Bob's guide (http://www.sagehill.net/docbookxsl/ImageSizing.html)

for all images.

I can't see anything at http://docbook.sourceforge.net/release/xsl/current/doc/fo/index.html

I guess I need to add this to my customization layer?

Nat