I adapted the example given only slightly and had no real difficulty (other than you have to give it the Apache log format string to use):

#!/usr/bin/perl

use strict;
use warnings;

use Apache::LogRegex;
use Data::Dumper;

my $lr;

my $log_format =
q/%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"/;

eval { $lr = Apache::LogRegex->new($log_format) };
die "Unable to parse log line: $@" if ($@);

my %data;

open DF, $ARGV[0] or die $!;
while ( my $line_from_logfile = <DF> ) {
    eval { %data = $lr->parse($line_from_logfile); };
    if (%data) {
        print Data::Dumper->Dump(
            [ \$line_from_logfile, \%data ],
            [qw(*line_from_logfile *data)]
          ),
          qq{\n};

        # We have data to process
    }
    else {

        # We could not parse this line
    }
}
close DF;
[download]

With this, I got the following result (using Data::Dumper for output):

$line_from_logfile = \'192.168.1.100 - - [07/Dec/2008:04:24:39 -0600] 
+"GET /some/file/here.html HTTP/1.1" 304 - "http://www.some-referring-
+webserver.com/some/other/page.html" "Mozilla/4.0 (compatible; MSIE 7.
+0; Windows NT 5.1; .NET CLR 1.1.4322)"
';
%data = (
            '%{Referer}i' => 'http://www.some-referring-webserver.com/
+some/other/page.html',
            '%{User-Agent}i' => 'Mozilla/4.0 (compatible; MSIE 7.0; Wi
+ndows NT 5.1; .NET CLR 1.1.4322)',
            '%t' => '[07/Dec/2008:04:24:39 -0600]',
            '%r' => 'GET /some/file/here.html HTTP/1.1',
            '%h' => '192.168.1.100',
            '%b' => '-',
            '%l' => '-',
            '%u' => '-',
            '%>s' => '304'
        );
[download]

Hope that helps.