I left out a line. That wasn't even going through the proxy. Sheesh!

use strict;
use warnings;
use LWP::UserAgent;
use LWP::Authen::Ntlm;
use HTTP::Request::Common;

print "creating agent\n";
my $ua = LWP::UserAgent->new(keep_alive=>1); 
$ua->timeout(10);
print "setting credentials\n";
$ua->proxy('http','http://192.168.1.6:8080');
$ua->credentials('http://192.168.1.6:8080', '', 'IR\\nicolew', 'asdf')
+;
my $req = GET 'http://www.yahoo.com';
print "Getting site...\n";
my $res = $ua->request($req);
print "returning info\n";
if ($res->is_success)
{
  print $res->decoded_content;
} else
{
  print $res->status_line, "\n";
}
exit 0;
[download]

Before you complain about the credentials line, I want to let you know that I tried the username as 'IR\\nicolew', 'IR\nicolew', 'ir\\nicolew', and 'ir\nicolew'. Same result each time - 407. I don't know what's changed that the error is no longer 502 except they updated our firewall this past weekend and it must have made a difference.

Also, I'm wondering if I'm using the credentials method incorrectly. It seems to be for sites that require a password - not to authenticate against the proxy. If that's the case, how should I be authenticating against the proxy?