how about Config::General?

# myconfig
<ALERT1>
  source = /var/etc/myalert1.pl
  green = 0 - 20
  yellow = 21 - 40
  red = > 40
</ALERT1>
<ALERT2>
  source = /var/etc/myalert2.pl
  green = IN ('a','b','c')
  yellow = IN ('d', 'e')
  red = OTHERWISE
</ALERT2>
...
[download]

you still have to parse the values of your settings (like IN and OTHERWISE). but it's quite readable and parseable by Config::General.