Personally, I would say "No" because he did not declare using the token. If he had declared using both dial and token, then he has two effects that kick in at the same time so he can add a die then reroll, or reroll and add a die. But since he only declared using the dial, the Resolve Attack Effects, Modify Dice step was over as soon as he rolled the die.

Thoughts?

On this part, i'd say the attack effects, modify dice step is NOT over as soon as he rolled the die because you can still modify the extra CF die with a card for example.

Even so, the player can't then use the token.

They can't go:

Roll Attack, modify with CF dial (has not declared his use of the token), use Darth Vader, then use the CF token.

He could do the above if he declared to use the token at the same time he spent the dial.

Ok?

I didn't say the player could use the token, so what are you countering with your post?