[Machicolation]

yup. keying is the way. if your existing footage is on a white background you may be able to get away with reusing it.

Premiere Pro won’t do, go to AfterFX.

1. There are various effects that will key out the background
2. and various effects to clean the matte
3. and various effects to take out the matte spillover that you’ll get.

the help file explains them all