How would I go about audio modulating my Tesla coil so that it can be controlled by a keyboard of the musical sorts?

I used these videos

well, asuming you already know how to audio modulate the tesla coil, its a simple means of getting the audio output of your keyboard (the musical kind) , and putting a resistor on it, maybe 100ohm would be ok if not a bit excessive, then have that line, go to your audio modulation input. just make sure you also link the negative of the audio line also to the ground of your tesla coils power supply.

If your tesla coil already has a transistor in there being unused, which is meant for audio modulation, then just hook up the auio line directly to that.

you should post the schematic used for your tesla coil, as it generally varies between circuits. for instance if it uses a 555 timer, the audio modulation input would go to pin 5.
depends on your power supply configuration.