You decide to take her over through her mouth. Your previous attempt was quick, but you plan to make this last.
You float through the window, and hover right in front of her. Admiring her pensive, cute face and shapely figure, you smile at the thought that soon, you'll be wearing her body - and no one other than you will know that it isn't Noel walking and talking.
Slowly, you reach out a finger and touch her lips. She is visibly startled - it looks like you do have some tangibility when you want to. She raises her own finger up to touch her lips. You brush that out of the way and reach your entire hand forward, forcing her mouth open and - to you - sinking your hand into her mouth all the way to the upper-arm.
Noel starts thrashing about, trying to grab on to your arm, which, sadly, her fingers just keep passing through. No matter. It's not like she has a chance of choking, since you can feel the air passing through your translucent arm as she breathes. You push your other hand through your arm, and slowly work your way in, as though squeezing through a tight opening of a tent.
Inside her throat, your fingers find purchase on who-knows-what. Perhaps her soul? By the feeling, it's certainly not anything physical. You pull, and silently clamber in. Your left arm goes into her left arm, and you feel it as though pulling on a warm, comfortable glove. Right arm into right arm...body into body...as you slip on more parts of her, her convulsions gradually slow and stop.
Finally, saving the best for last, you raise your previously-bowed-for-entry head, and it slips smoothly into hers. Her silently screaming mouth and eyes crinkle, then conform to your spiritual ones.
You touch your face, tentatively, and run a questing finger over Noel's freckles, moist lips, and pert nose. "Hello," you try, and Noel's bright, chirpy voice emerges. You walk over to the mirror and smile, and the Noel in the mirror smiles innocently back at you.