This feature appears to be available in 3.5 - there's an "add file" button,
which you can use as many times as you like.

The "add file" button is in KDE 3.4.3 too. The problem is: when you have a
directory with 60 files to print you have to use this button 60 times and
select in 60 dialogs one file each.

Ah, I see. So the simple solution would be to allow multiple files to be
selected in the Open Dialog there, which seems to be the correct thing to do
anyway.

Exactly

Created an attachment (id=15485) [details]
patch to implement

Here's a (slightly tested) patch to implement this. Apply to kdelibs/kdeprint/.
Hope it's useful!

SVN commit 526968 by tibirna:

Allow adding multiple files to the to-be-printed list
Thanks to Philip Rodrigues for the patch. I tested it.
BUG:114384


 M  +3 -3      kfilelist.cpp  


--- branches/KDE/3.5/kdelibs/kdeprint/kfilelist.cpp #526967:526968
@@ -243,9 +243,9 @@
 
 void KFileList::slotAddFile()
 {
-	KURL	fname = KFileDialog::getOpenURL(QString::null, QString::null, this);
-	if (!fname.isEmpty())
-		addFiles(KURL::List(fname));
+	KURL::List fnames = KFileDialog::getOpenURLs(QString::null, QString::null, this);
+	if (!fnames.empty())
+		addFiles(fnames);
 }
 
 void KFileList::slotRemoveFile()

Closing old Resolved status bug.