use LWP::UserAgent;
use HTTP::Request::Common qw/POST/;

$ENV{HTTP_PROXY} = 'http://127.0.0.1:8888';

my $ua = LWP::UserAgent->new;
$ua->env_proxy;

$ua->request(POST 'http://example.org/url/',
	Content_Type => 'multipart/form-data',
	Content => [
	    '0=0',
	    '1=1',
	    '2=2'
	]
);