How to add Properties to an Entity in code?
I've been researching and playing around with the ECK module all day and have managed to answer my own question. Hopefully someone else will find this helpful.

To the example code listed just add these lines before the save() function is called:

$entity_type-&gt;addProperty('title', 'Title', 'text', 'title');
$entity_type-&gt;addProperty('uid', 'Author', 'integer', 'author');
$entity_type-&gt;addProperty('created', 'Created', 'integer', 'created');
$entity_type-&gt;addProperty('changed', 'Changed', 'integer', 'changed');