Here's what I came up with:

This goes in the on JOIN:

Code:
  set %a $hget(userchans,$nick)
  if ($chan isin %a) {
    set %userchans $reptok(%a,$chan $+ $chr(124) $+ *,$chan $+ $chr(124) $+ $ctime,1,32)
  }
  else set %userchans $addtok(%a,$chan $+ $chr(124) $+ $ctime,32)
  ;echo -s userchans: %userchans
  .hadd userchans $nick %userchans


This goes in the output area:

Code:
  set %a $hget(userchans,%nick)
  set %b 1
  set %c $numtok(%a,32)
  while (%b <= %c) {
    set %d $gettok(%a,%b,32).data
    set %e $hget(channumnames,$gettok(%d,1,124))
    set %f $duration($calc($ctime - $gettok(%d,-1,124)))
    set %g $addtok(%g,%e $+ $chr(124) $+ %f,32)
    inc %b
  }
  echo 4 -s %nick %c : %g


If anyone has any code suggestions, I'm all ears (eyes).

I registered; you should too.