Sorry, didn't make it before midnight...
I hope you like "explain like I'm five".
Here it is:
FIRST!!!!!!!!!
Cover your guitar properly!!! Soldering iron can cause some serious damage to guitar finish. You can use some clean rags or something else.
SECOND:
Be very careful when stripping wires from isolation. J50BC is a ~15-year-old pickup, so you've got to be gently with it. (like a swedish lady)
This is JE with jumpers in the "BYPASS" position (when the pot is pulled, JE is bypassed):
This is JE with jumpers in the "GAIN SWITCH" position (when the pot is pulled, gain it turned off):
Here are pics of J50BC wires:
IN_SIG: Black wire from J50BC
IN_GND: Green + wire without isolation from J50BC + guitar ground
Here is the OUTPUT SECTION:
Here is how it looks like at the output jack: