The Master Zend Framework site has posted a tutorial wanting to help you understand external form element dependencies with help from FormElementManager.

Zend Framework 2, like all great PHP frameworks, provides thorough infrastructure for creating forms in your application. Whether that’s form objects, form elements, fieldsets, validation groups or that they interact with so many other components in the Zend Framework 2 default libraries. But how do you handle external dependencies? [...] So what if you need a custom form element in your application, one which will render a list of articles from a database table? [...] In today’s post, we’re going to look at how to create such a custom element, extending the existing select element.

He walks you through the steps you'll need to make the custom element and hook it into the FormElementManager for correct use:

• Create a New Form Element
• Implement the getFormElementConfig Method
• Create a New Form Object
• Instantiate the Form Via the FormElementManager

Code is included for each step of the way so you can ensure you end up with a working example.