I'm back, made some advances.
I measured the voltage on the battery terminals while charging and while not charging. Charging will rise the voltage by .1 or .2 V at most, so it won't burn my leds.
I soldered a connector to the battery terminals and glued it to the side of the headphones, the next step is to build the 3-point piece so that I can connect it or disconnect it at will.
I couldn't get a hold of those famous irleds so i'll just shave off some normal ir leds to improve the angle.