Relatively easy mod to turn your wired keyboard into a detachable wired keyboard.
Step 1: Open the Case
Opening the case was pretty easy. Just grab an old plastic card and feel around the edges until you find the clips. Poke at them with the edge of the card and gently pull the case apart.
The front face slid right off for me, and there were two more clips on the back side holding the board in place. Once those were off the board came right out.
Step 2: Evaluate the Pinout
The pin-out for the USB cord had 4 colored wires and a ground, so I made the assumption it was probably a mini-USB without the 5th wire. That means I needed the F end of a M/F mini-USB cord to splice with this existing cord. I picked this guy up from Amazon for five bucks.
Step 3: Cut and Strip
I cut the M/F mini-USB and stripped the side connected to the F end. Then I cut the keyboard cord and stripped the side connected to the keyboard. After gently peeling back the shielding and folding it out of the way, I was left with 4 small wires on each side.
Since the wires inside the main wire are quite small I wasn't able to use my wire stripper. Instead I used my soldering iron with a wide d-series tip to melt away the plastic. I placed the wire on a wood block, pushed down lightly on the wire with the soldering iron, and then drug it outward to the cut end.
Step 4: Twist and Solder
Before I started this step I twisted all the wires together losely and made sure the keyboard would actually work. Once i was sure I wasn't wasting my time with a bad cord, I disconnected everything and then slid a small heat shrink onto each of the wires, that way i could slide it over each connection after it was made. Then I matched up the colors twisted each pair together, and applied a little solder.
NOTE: I really should have used some flux. Either the type of wire, or the process I used to strip them made it very hard for solder to stick.
Step 5: Heat Shrink
After all the wires were joined, I slid the individual wire heat shrink's into place and used a hot air gun to seal them. Then I slid the cord heat shrink into place and hit with some heat as well. I could have used two larger heat shrinks since there's a little exposed, but I figured it would be good enough.
Step 6: Fit Wire to Case
Once I got the wire positioned so the board could be seated back on the lower case I realized the end of the cord was just a little too large to fit under the board comfortably. I sanded down the end until the board rested comfortably on top of it, then a took a little more off and snugged it up with a cardboard shim.
Step 7: Fit Case to Wire
The top half of the case was slightly too wide for the plug, so I shaved the opening a little wider with a hobby blade. After that the case went together smoothly and I was able to plug in the cord!