CRM 2011 Disable out-of-the-box ribbon button based on value from selected row on HomepageGrid or SubGrid

Greeting.

I'm trying to find an example that will get me started with the following scenario.

In HomePageGrid ribbon (and also sometimes SubGrid ribbon), I need to enable/disable a out-of-the-box button (Delete) based on the value from the selected row.

Does anyone know of a step-by-step walkthrough for that scenario?

Thanks,

Frank