Croissanga is a WordPress plugin that gives you the ability to add, edit, and delete your Xanga posts directly from WordPress.
See INSTALL for more. In a word: upload the croissanga/ directory to your plugins directory and activate it. You must have the PHP CURL module installed.
Previous versions did not have editing and deleting functions built in. You will have to replace your old plugin file; if you hacked on it, I'm sorry.