How to disassemble SNES controller plug, and cable question?

[sonic2041]

I have shorter versions of that wire. It's diameter is roughly 0.150 in. and SNES cord is roughly 0.175 in. so it would be smaller. Its also kind of stiff, I'm sure it would loosen up over time. I'm sure using the shielding for the fifth wire would work. I'll try to think if there are better options and post if I come up with something. I know I used Ethernet wire in the past (lol) It worked OK, but that isn't ideal. I wonder if there is a place where you can buy multi-lead wire for cheap.