LightRoom, how to go from customer list to collection?

kdog

Say you create a proofs gallery for a client. After reviewing the proofs, the customer sends you a list of photos they want touched-up. Is there an automated way to input their list and somehow turn this into a collection in LR, or at least flag the photos in some way so I don't have to hunt each one down by hand? The by-hand method is too time-consuming and error-prone. I found a fairly convoluted way to do it using a Windows script, but it's not perfect. I'm wondering what the pros do.