Assuming that ID number 15 is your listbox containing your chosen channels (unselected):
Code:
var %i = 1
while $gettok($didtok(15, 44), $+(%i, -, $calc(%i + 3)), 44) {
  .timer 1 $calc(%i / 2) describe $ifmatch is away: stuff here
  inc %i 4
}

If you wish to use /msg instead of /me, switch the word describe to the word msg.

The timer should keep you from flooding yourself off by spacing out each group of messages.

DALnet: #HelpDesk and #m[color:#FF0000]IR[color:#EEEE00]C