Good work, nice to see it done in native mIRC scripting.

As an added note, one could kinda cheat using the msscriptcontrol object to interpret vbscript code (good find tidy), more specifically the datediff() function. I prefer your way, because well, we're not vbscripters, we're mIRCscripters.

Code:
alias datediff {
 [color:red]  [/color] 
  /*
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  Usage: $datediff(begindate,targetdate).property
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  Properties: 
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  "yyyy" Year 
  "q" Quarter 
  "m" Month 
  "y" Day of year 
  "d" Day 
  "w" Weekday 
  "ww" Week of year 
  "h" Hour 
  "n" Minute 
  "s" Second 
 [color:red]  [/color] 
  Example: //echo -a $datediff(18/03/1982 08:30,3/05/2005 15:10).s
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  */
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  if !$ctime($1) || !$ctime($2) || !$istok(yyyy q m d w ww h n s,$prop,32) { return }
  var %a = a $+ $ticks, %b = Datediff( $+(",$prop,") ," $1"," $2")
  .comopen %a msscriptcontrol.scriptcontrol
  if $comerr { return }
  tokenize 32 $com(%a,language,4,bstr,vbscript) $com(%a,eval,3,bstr,%b) $com(%a).result
  .comclose %a
  return $3
}

I should note that when specifying the yyyy property to see the difference in years between the two dates, it ignores the months and time. Just looks at the year of the date.

When using .s to get a result in seconds, one could use $duration on it to get the result in "wks days minutes seconds" format.

Greets