I found the following code in the LWP docs:

# Create a user agent object
use LWP::UserAgent;
$ua = LWP::UserAgent->new;
$ua->agent("MyApp/0.1 ");

# Create a request
my $req = HTTP::Request->new(POST => 'http://search.cpan.org/search');
$req->content_type('application/x-www-form-urlencoded');
$req->content('query=libwww-perl&mode=dist');

# Pass request to the user agent and get a response back
my $res = $ua->request($req);

# Check the outcome of the response
if ($res->is_success) {
    print $res->content;
}
else {
    print $res->status_line, "\n";
}
[download]

It seems to me that by changing the POST => 'http://search.cpan.org/search' and the $req->content('query=libwww-perl&mode=dist'); lines you can change the example into something you want.

Arjen