Hm... That's kind of difficult. You should use either e-mails with attachments or some mirc script with its own file sharing feature. It's difficult to find this kind of thing in a script, cause mirc already has DCC, but i think i had seen a file server addon at
www.mircscripts.org . I don't know where it is now!!!
Note: In order to file-share with others via mirc without using DCC, both users must have the same file-sharing system added on mirc.
Hope helped!