Being a gambler and do-it-yourselfer, I decided to take apart one of my two Sleek Wireless Accessories to see if I could direct wire it to my UE Pro10s, using the UE cable and pin plugs. I'm not finished yet, but so far I successfully opened the Sleek Wireless Accessory, desoldered the stock connections, and soldered in my UE 10 cable.
Here are some photos of progress to date. In another 30 minutes I'll start it up and see if it produces sound. If my solder connections are good, and I get it all back together, I don't see why it shouldn't work, but in any case I'll post a progress report.
The Sleek Accessory is quite easy to pop open. I used a small screwdriver and pried it open around the rubber grommets on each side. It just popped open. The battery is glued into place with some soft sticky stuff, but it pries loose quite easily. As the photo shows the circuit board has a metal surround on the bottom and one side, which I think is there to hold it in place in the case.
In these photos the UE cable has already been soldered to the circuit board. A delicate job, and not for someone without strong soldering skills and experience.
The battery, pictured to the right, takes up about half the space in the small case. The circuitry takes up the rest. The circuit board is quite small -- oh the miracle of today's electronics. That small board produces amazingly high quality wifi sound.
This photo show the flip side of the circuit board and battery. It's all made in China, of course.
I'll report back in a few hours on whether this has been successful.
Photos of inside of Sleek Wireless Accessories
makes me wish i could solder better 
