The tuned teeth (or lamellae) of the steel comb is typically set to a chromatic scale. To change the tuning would require adding or subtracting material to an individual tooth with some trial and error and a good ear. Changing the length would cancel the action of the pins on the revolving cylinder so that is not a good idea.
If you think the scale you have meets your tuning definition then it would be far easier to make a new scroll to change to the melodic and harmonic content you desire. If you are starting from scratch and have the tools you should make a system to be able to change the scrolls so you have a diversity of songs.
Here is a reference to tuning the reeds on a harmonica since this is adding and subtracting material related:
Information on how to tune lamellae as used in a Karimba:
Here's a place where you can make your own music box tunes by using
punchable paper strip musical movement:
I am not entirely certain that using tuning fork math is the right place for a series of metal bars as found in a music box comb so I have done some more searches and found a reference that covers much more here: