I understand that your config file is probably plain text, but here's an option using Data::Dumper and require.

Start with a configuration format, like a HASH:

perl -MData::Dumper -e '
  $conf = {
    DEVICE => 'eth0',
    ONBOOT => 'yes',
    BOOTPROTO => 'static',
    TYPE   => 'Ethernet',
    IPADDR => '10.9.0.200',
    NETMASK   => '255.255.0.0',
    GATEWAY   => '10.9.1.254',
  };
  open( $fh, ">", "monkConfig.txt" ) or die;
  print $fh Data::Dumper->Dump([$conf],["config"]);
'
[download]

Creates a file with this format:

$config = {
            'TYPE' => 'Ethernet',
            'ONBOOT' => 'yes',
            'NETMASK' => 255.255.0.0,
            'GATEWAY' => 10.9.1.254,
            'DEVICE' => 'eth0',
            'IPADDR' => 10.9.0.200,
            'BOOTPROTO' => 'static'
          };
[download]

Then use require to access the data:

perl -le 'require "monkConfig.txt";
  print $config->{'TYPE'};
'

__output__
Ethernet
[download]

...then redo the Dump to write changes back to file. Yeah, probably a bit more tedious then Tie::File, but imagine the possibilities!