I see... maybe a loop is required here then.
'domsg' will be the custom msg alias.
alias domsg {
var %i = $numtok(%m.ptype,32)
while %i > 0 {
var %chan = $gettok(%m.ptype,%i,32)
if ($me ison %chan) { msg %chan $1- }
dec %i
}
}
and use: /scon -at1 domsg MP3 Player online