FTP requires the cPanel username and password (unless you make a separate account for FTP otherwise in your cPanel, which you can assign a different username and pass I believe, and only allow them to FTP a certain part of the site). Otherwise, if you want to install IPB, just create a database in MySQL, upload the forum software via FTP where you want it, and read the readme/IPB support site for installation. It's not too hard to install, and it's actually quite easy. The only thing is, uploading will take some time, but everything else only takes a minute or so. Also, don't forget to make sure MySQL is set at mysql.x10hosting.com (to cut on support threads).
Otherwise, once the forum software is uploaded, go to
http://*your site*/*path to IPB*/admin/install.php OR
http://*your site*/*path to IPB*/install.php, wherever it's located. Once you run that, simply follow the instructions in the install file, and you're all set. Don't forget to remove the install.php file from your account once you're up and running.
Otherwise, I can do it for you, just as long as I don't get your main user and pass. You'll need to make the database though once you get cPanel access.