The holder has to remain in the same orientation as in the picture.
You could always run your system with the sticks in place. The heat should weaken the TIM if you're quick enough getting them out. At least my GSkill Snipers could do that. The TIM is pretty solid when they're cold but after a gaming session they loosened up pretty good.
Could try that when I'm feeling adventurous. Saves having to go the store to buy a heatgun.