Hi Michael!
In order to apply this change, you need to decorate the getIconSizes() method of the
\XLite\View\ItemsList\Product\Customer\ACustomer class.
You will see that now thumbnail sizes are hard-coded to 160x160px.
The basic guide about how to perform a decoration is here:
http://kb.x-cart.com/display/XDD/Step+3+-+applying+logic+changes
Finally, I will pass the feedback about creating options for thumbnail sizes to the team.
Tony.