If you want to force LWP to connect via some specific IP/port you can set this IP/port as an address of proxy. For example:

use LWP::UserAgent;
use HTTP::Request::Common;

my $ua = LWP::UserAgent->new;
$ua->proxy(http => 'http://1.2.3.4:5678/');
my $response = $ua->request(GET 'http://my.domain/path');
[download]

--
Ilya Martynov, ilya@iponweb.net
CTO IPonWEB (UK) Ltd
Quality Perl Programming and Unix Support UK managed @ offshore prices - http://www.iponweb.net
Personal website - http://martynov.org