I'm looking to add a custom set of classes to the K2 itemContainer. In my code I've noticed in my category list all my itemContainers have a secondary class that is itemContainerLast? i would like to replace this with a custom class or multiple classes. I was looking for a field where you can add this, but have not found anything. Is this something that is per template or is it just a field that i'm missing generated by categories? I'm using Joomla 2.5

Looks like:

<div class="itemContainer itemContainerLast">

Want something like:

<div class="itemContainer customClass1 customClass2">

You need to add these classes directly to your template, this post will help you locate the files you need to change .
getk2.org/documentation/tutorials/174-templating-with-k2-and-the-concepts-of-sub-templates