I just installed two 2.6CE chips tonight, but unfortunately both were in 1.6 Xboxes so I had to use the cables. If you get no joy from the vendor and can't get hooked up due to locations or other circumstances I could provide tips for hard-wiring this in. It shouldn't be too difficult, you'd be soldering one end of a wire to the alt-5v like you would have to do anyway, the other end would be about as tricky as soldering in the HDD and LAN connections. Problem is that if you ever needed to remove the chip for one reason or another you would need to unsolder one end of this wire. Definitely work all angles you can to obtain the proper wire, but if you strike out an alternative is available.
-Whoopin'