use strict;
use Net::SSH2;

my $ssh1 = Net::SSH2->new();
$ssh1->connect($host1) or die "connect to SSH1 failed";
$ssh1->auth_password('user', 'pass') or die "auth1 failed";
$ssh1->tcpip($host2, 22, '127.0.0.1', 9922);

my $ssh2 = Net::SSH2->new();
$ssh2->connect('127.0.0.1', 9922) or die "connect to SSH2 failed";
$ssh2->auth_password('user2', 'pass2') or die "auth2 failed";

# ... as many hops as you need ...