I used to keep a giant live well full of herring in the spring. LOL !!! Actually it was a swimming pool !!! anyway, what I would do as far as freezing them was to salt them live. Then rap them in butchers paper, ziplock bag them and freeze. Koscher(sp?) salt was the ticket. Though a friend of mine gets me this other stuff I can't remember the name at the moment.
Had to close my operation down though when fish and game changed all the regs and the fear of the epa for how I ran my well. Although there wasn't one dam thing I was doing that would pose a threat to the enviorment.
I like using artificials now and then but I get the best overall results with live or my own fresh frozen bait.