8
           
            
                
     
    
    Maybe doing with Javascript would be the easiest.
In storyform.inc.php replace
 $submit_btn->setExtra('accesskey="s"');  
by
 $submit_btn->setExtra('accesskey="s"  onClick="myConfirm()" );  
In your xoops.js, you add this confim function:
 var windowHandle; 
function myConfirm() { 
    windowHandle = window.open('confirm.html','windowName','width=600,height=320'); 
    if (!windowHandle.opener) 
        windowHandle.opener = self; 
    return false; 
}  
You need a confirm.html (regular html file, mind the paths) with at the inside:
 I do solemnly swear ..... 
<FORM> 
<INPUT TYPE="button" VALUE="Okay" onClick="opener.document.storyform.submit();self.close()"> 
<INPUT TYPE="button" VALUE="Cancel" onClick="self.close()"> 
FORM>  
It's from an old code example used to confirm a delete in a database.
edit:removed superfluous tick