Going to update this when I get home tonight.
-Update
Opened up my Key, the Cell Battery is a Varta 625U 1.5V Battery
the Stock battery will not light up the LED that I have.
In addition, the LED that I have (typical small 5?mm) is a hair too wide (stock bulb is probably a 3mm)
would have to enlarge the hole for the light a tad on the key.
In addition, would need to get two flatter 1.5V cell batteries to bump the voltage to 3v