Had to create a plugin. Guess this means I'm getting back in the groove. ;P Referring back to these posts, this plugin will make a button on your edit post/page making it possible to paste some code you wanted to show, select the code, then click "decode" – which will convert your < to < and > to > in the selection – so that it doesn't break your page.
Installation instructions:
Download the Decoder Button plugin. (Save that page and just make sure the rename it to "decoder_button.php") Upload it to your wp-content/plugins folder, and activate on the plugins page in your wordpress admin interface.