well, as a VERY generic (basic) start for you:

on *:input:*:/.timerAWAY 1 300 /away Auto-idle Away

or

on *:input:*:/.timerAWAY 1 300 /awayalias

Code:
/awayalias {
  away Auto-idle Away
  command1
  command2
  etc
  etc
  etc
}


Now granted this could likely cause HIGH cpu usage as everytime you type something and send it the timer'll restart. Also, it might help if you showed us the away system you're using so that we might be able to help you further

Those who fail history are doomed to repeat it