Hi,
Edit the file "mailform" of the view "order" for your backend template via the menu Display>Views and change the code:
<input type="hidden" name="data[order][mail][cc_email]" value="<?php echo $this->element->mail->cc_email;?>" />
<input type="hidden" name="data[order][mail][bcc_email]" value="<?php echo $this->element->mail->bcc_email;?>" />
to:
<br/>CC:<input type="text" name="data[order][mail][cc_email]" value="<?php echo $this->element->mail->cc_email;?>" /><br/>
BCC:<input type="text" name="data[order][mail][bcc_email]" value="<?php echo $this->element->mail->bcc_email;?>" />
and you'll be able to see these fields at the bottom of the popup.