If you can get it to eat frozen, then sure. You might use something like Kent Zoe. Try feeding every day and just observe how much it eats to get a feel for how big of an appetite it has. When you feed it live items like crabs just put one or two in at a time, and make sure to remove any leftovers so not to foul the water.
Varied diets are not as important as you might think. The main reason to keep a varied diet, in my opinion, is to allow for variables so that if you are unable to obtain a certain food type the specimen will also be conditioned to other food types. In some octopus and cuttlefish, a certain prey item may comprise 70-80% of its diet.
Vitamins can be good, but what type of vitamins are you planning on using. I have never administered vitamins to any cephalopod on a regular basis.
I wasn't sure about the vitamins, I've heard of people soaking their fish food in a liquid vitamin but didn't know if it was necessary for a ceph. I was quite dismayed when my briareus returned to me the silverside fish I had given him to eat and have since discovered he loves frozen scallops and shrimp. I will take your advise, Greg, and continue to offer him other foods in case I can't find his favorites. All the advise I get from the wonderful members of Tonmo is so much appreciated. Thank you.
Thanks for the comments on the vitamins. I add B's to my reef tanks but have refrained from the octo tanks since the biology is so different. I add calcium to my top off water and extra to tanks that have shell creating inhabitants (and then have to deal with the coraline on the glass ). The octos get the same top-off but no additional supplemental calcium and this seems to work but you used the term regularly and I am curious if you use an immune boosting or other vitamin on an occassional basis with the cephs. Of particular concern are my newest hatchlings.