use LWP::UserAgent;
require LWP::Protocol::http10;

my $url = "http://localhost/";
my $ua = LWP::UserAgent->new();
my $req = HTTP::Request->new(GET => $url);

# make HTTP/1.1 request
LWP::Protocol::implementor('http', 'LWP::Protocol::http');

$ua->request($req);

# make HTTP/1.0 request

LWP::Protocol::implementor('http', 'LWP::Protocol::http10');

$ua->request($req);