For the sport button, I bought LEDs off amazon and used some thin gauge wire I had to solder to them. I did not glue them to the button circuit board, but rather just glued them together and then soldered to them with the wires. It's pretty delicate, so getting it back in the switch panel is tricky. But cut the plastic cage for the button with a dremel so the wires have room to go through.

Amazon LEDs: https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

Here are the LEDs set into the button. REMEMBER -- the red LED needs to be reversed! You can see where the wires go through the plastic:






This is the wire that goes from pin 17 of the switch center (this is the line from the sport button switch that grounds the DME in the M3 to signal sport engaged). In line with my wire is a resistor that simulates the 1k resistor in line of the sprint booster button as shown in the schematic above. This wire plugs into the BMW connector plug that connects to the sprint booster switch.



Success! Makes the car feel like it has 30 more HP.