Well, for the idle script you could make a timer for when mIRC Starts up to trigger an alias. Now this don't account for your idle time on the server.

Code:
On *:Start: {
  dll hOS.dll AddStatusBar noxptheme sizegrip
  dll hOS.dll SBSetPanels 100 400 -1
  .timeridle 0 1 idlecnt
}

alias idlecnt { 
  if  ($duration($idle) == 0secs) { return }
  dll hOS.dll SBSetData [color:red]<Panel number>[/color] $duration($idle)
}


It's whenever you send any command like /echo, /msg, /say.

Edit: As you've already created a StatusBar in another On Start event, you can remove the AddStatusBar and SBSetPanels lines.

All the best.

-Andy