You can use specific product images for your Amazon instances by modifying your field mappings.
- Go to Settings > Channels
- Click on the XML Mapping that's appropriate for your specific Instance
- Change the "Type of XML to Edit" to "Product Images"
- PT1 through PT8 represent the product images on Amazon. Map a media field to each of these to specify what images to use.
- Click "Save Settings" at the bottom of the page