mvi-
This is possible.
The first thing you will need to do is add the Notes field as a linked field to the Contacts table, since the Customer List screen is based off the Contacts table and by default the Contacts table does not have the Notes field in it. (Take a look at THIS if you need help with linked fields)
Then you can customize the CRMQBO_CustomerList screen and add the Notes field as a column to the grid.
-Michael