how put narrow non-breaking spaces before punctuation marks

Hi,

I am using docbook 5 for publication in French, so I need to place the usual narrow non-breaking space before strong punctuation like colon, semi colon, exclamation and question marks.

How to proceed ?

Should I introduce them from the start, in the docbook manuscript ? Then how? 

Or can we do it automatically with the xslt ? Is there any parameter for that ?

[I am editing with Oxygen]

Thanks for your help,

Patricia