formatting numbers

Hello!

I have a little problem with the format of my numbers... Living in
Switzerland, I would like to use a separator other than a comma (,)...
Is it possible to use ' ???
By just replacing the commas by an apostrophe, it obviously doesn't
work... Is there a way to do this???

<xsl:value-of select='format-number(montant, "###,###,###")' />

Thanks!
Neil.