Here are some pics and info, and a
guide is available. The pictured mod is very close to one of the official schemes (Twin Stick Type B), and only requires using the in-game control scheme customization to assign the weapon inputs to the stick "click" buttons. In the final version of this mod, I went ahead and just used the trigger buttons, which also work fine.
For this mod I have used black wire for ground throughout. I only had three colors of 26 AWG stranded wire for the mod pictured. Sorry for any confusion, and feel free to ask any questions you have!! If anyone needs higher quality photos, let me know (the originals are 3872 x 2592 resolution, not exactly good for web viewing, but maybe helpful to see
exactly where a solder point is

).
For the connectors, see a post of mine below for the part numbers and how to obtain them.
This is how I have configured the Xbox 360 buttons to map with the DC Twin Sticks:
EDIT:
I originally made a typo on the control scheme (swapped Left Stick with Right Stick). If you're doing a reversible mod (i.e. using JST connectors), there wouldn't be any problem. Hopefully this didn't cause anyone any problems.
Code:
XBOX 360 TWIN STICKS
----------------------------
UP Left Stick Up
LEFT Left Stick Left
DOWN Left Stick Down
RIGHT Left Stick Right
A Right Stick Down
B Right Stick Right
X Right Stick Left
Y Right Stick Up
BACK START
START PAUSE
GUIDE N/A
L. Bumper Left Turbo
L. Trigger N/A
L. Stick Left Weapon
R. Bumper Right Turbo
R. Trigger N/A
R. Stick Right Weapon
Complete modded controller PCB.Attachment:
File comment: Complete (top)
IMGP2522.jpg [ 165.21 KiB | Viewed 15724 times ]
Attachment:
File comment: Complete (bottom)
IMGP2517.jpg [ 162.37 KiB | Viewed 15707 times ]
Left and Right sticks.Attachment:
File comment: Left Stick
IMGP2512.jpg [ 142.34 KiB | Viewed 15707 times ]
Attachment:
File comment: Right Stick
IMGP2511.jpg [ 182.52 KiB | Viewed 15714 times ]
Buttons.Attachment:
File comment: START and PAUSE
IMGP2507.jpg [ 125.34 KiB | Viewed 15709 times ]
Attachment:
File comment: LT & LW buttons (top)
IMGP2508.jpg [ 111.27 KiB | Viewed 15704 times ]
Attachment:
File comment: LT & LW buttons (bottom)
IMGP2513.jpg [ 171.95 KiB | Viewed 15707 times ]
Attachment:
File comment: RT & RW buttons (top)
IMGP2509.jpg [ 119.34 KiB | Viewed 15703 times ]
Attachment:
File comment: RT & RW buttons (bottom)
IMGP2515.jpg [ 161.92 KiB | Viewed 15723 times ]