My favorite ways to access LastPass on a computer that is not mine is installing the plugin on a portable browser.  A portable browser is a web-browser; either Firefox, Opera or Google Chrome that you launch from a thumb-drive.

Install one of these on any thumb-drive you have laying around. That old 256  MB one that you never use anymore will be fine. Setup that browser with your bookmarks and all the plugins that  you use at home. Now install the LastPass plugin and you are ready. Insert your thumb-drive in the computer you would like to use and launch the browser. Always use the onscreen keyboard to login or submit any private information.