if u want mirc to downlaod form multiple clients just write a script to do it, i mean how hard could it be,
ctcp ^*:dcc send etc etc open the socket read the file write it out, keep track of whats written already, make a choice on the second sender where to start, build a table of sections already downlaoded, keep track of what each downlaoders section is writting to, have to stop responding when u reach a already downloaded section and hop the sender well repeatedly offer you the file to resume some other part, etc etc etc <grin>
mahahhaa and after all that you find that a single sender is likely to use all your bandwidth anyway!

PS : anyone not reliasing im against this.