Personally, I haven't had to starve any of my aros. I've had luck with a few different ways to get them to take pellet, and other prepared foods.
1. Use a food that you know they will take right away. Have some pellets ready and throw a little bit of their favorite food in to stimulate the feeding response. Once the aro starts gulping his favorite food...throw the pellets in next time and he might take the pellets without hesitation. Even if he spits them out a few times...at least he's recognizing it as food.
2. Put the food in the flow of the filter return. Sometimes that movement will attract the aro and then they'll take it. My Jardini will sit there...staring at the pellets, and wait until they float into the return current...then he eats.
3. If you have other fish that eat pellet and prepared foods...that may assist with the aro identifying them as food. My silver transfered to pellet this way...he used to watch my dats attacking the pellet and then one day he decided to give them a try...and the rest is history.
Hope this helps.