It is possible to import to Insert a CSV file including a list of visitor IDs. This list can then be used in audience filtering - you can build a segment including all visitors in this list or all visitors who are not in this list, and mix and match with other filters.
Under the 'Account' tab, click on "User Lists". You can see the lists you've already uploaded to your account and can add a new User List.
The uploaded file should have a .csv type. It should consist of a visitor ID per line while the first line should include the string 'visitorID'.
Once the upload is complete, you will see the new list in the table along with the number of devices in the list.
You can now create an audience for an insert, and use the new "User Lists" tab under Audience.