When you accept the terms of service for the wireless network, you should be taken to a page that has a link for (temporarily) installing a wireless printing client. This page can be accessed at http://m.lapl.org/wireless. You can also go to the branch page of the branch you are at, and click on the "Wireless Printing" link under Resources & Services on the right-side of the page. Illustrated instructions (in PDF format) can be found here.