When you want to make bulk changes via a Wizard, you have the ability to populate the wizard based on a file, rather than going through and selecting individual items.
Creating a wizard by importing a file
1) From the main menu in the Back Office, expand the Wizards & Imports heading, then click on Wizards.

2) Select the type of Wizard you want to create, then click on Create Wizard.

3) You'll see a menu like the one below – choose Import List of Codes:

4) This will take you to a page that enables you to use a CSV or Excel file to populate the wizard. Each code must have its own row in the spreadsheet, as below:

5) Once you have selected the file, it will show you the items added:

6) If you are happy with the selection, you can then click on the Create Wizard button at the bottom of the page, and carry on using the wizard as usual.
NB: Wizards are processed sequentially, so will be 'queued' and processed one after another.