Yes, you can import a database of barcodes. If you already have them as a list, separated by returns, the easiest thing to do is copy paste the list into the multiple add window that comes up when you choose 'Add multiple' from under the Edit menu. (There is only one line in the multiple add window but it can take a list of hundreds of entries nevertheless.) Once it's pasted, hit the 'Add' button and the program will automatically go through the barcodes and search for the entries.
The search site the program uses for this depends on the site selected in the regular search window that comes up when you hit the plus button in the toolbar. So make sure that before you start the multiple search you have selected the site you want to use there. (Or set it to Cascade for the program to cycle through the sites until it finds a match.)