I've found 2 things really help a lot when feeding f/t. The first is to prescent so the snake knows food is coming and is ready to eat. If it is convenient, you could put a live mouse/rat in the room to prescent, then offer the f/t. That might help with the transition. If not, get some soiled bedding from a pet store. You can use this not only for prescenting the snake, but also to add some fresh scent to the f/t.

The second is to make sure the f/t rodent is plenty warm, especially the head. After you have thoroughly thawed the prey item, use a hair dryer to get it warmed up. Remember that the normal body temp of a rat or mouse is a few degrees above that of a human. I try to get the entire body of the f/t to what I guess is the right temp, then get the head a few degrees above that.

Finally, if you really want to convert a snake to f/t, don't be afraid to use some tough love. If it refuses the first time, don't give in and give it live. In my admittedly very limited experience in this, since I usually feed live, most snakes that are usually good feeders will take the f/t after missing a couple of feedings even if they didn't want anything to do with it the first time.