I have recently encountered this problem in a magento project where we needed to create a custom image attribute in magento admin and import images against that.I tried using conventional import but it didnt work.
I created a dataflow profile in magento admin to get the task done. Go to System -> Import / Export -> Dataflow – Profiles and click on Add New Profile.
In field mapping section map field against database fields as shown in screenshot.
After this Click on Save and Continue. Go to Upload file and upload the file with sku and ebay_images fields or anything else you may have defined.Finally, run the profile you will see all images uploaded and assigned.