Okay so I was wondering, because Winterhold (the Wizard College) is under the power of the Imperials (one of the main-line quests), can I get it BACK into Stormcloak control?

If this is no, can Dawnstar be captured by the Imperials?

Thanks

At the beginning of the game, Winterhold is under Stormclack control. It only falls to the Imperials during the Legion questline after Dawnstar is taken.

Edit: If you mean the quest you get near end of MQ involving civil war, then just do one of the civil war questlines.

so the Imperials can take Dawnstar?

Also, it was handed over during the meeting at the Greybeards, where they ask for Riften, but I said Winterhold was a better deal.