I don't understand your picture. Yes, you need a ground to complete the circuit. And without manipulating the data pins, you will be limited to a charge rate of 100mA.

ladys and gentlemen. assuming you are happy with only the 100ma cap then could you not logically just connect the wires to the battery terminals and allow that to charge it. leaving the usb port free?? i have had to do this once or twice in emergency situations when i didnt have the correct charging cable but had a damaged usb + laptop.

Yes, you will need to ground to any metal point to complete the circuit. I just sandwiched the wire between the sim and metal sim holder.

I'm in the process of doing the same thing to my Sensation. I wanted to make sure that the Touchstone charger would support the weight of my phone in it's case, so I took the short cut of using parts from a microUSB charger to route from the induction coil terminals to the charge port. I'm halfway through routing all the necessary connections to go through the board instead of the charge port. In the attached picture, I've highlighted 2 test points that will let you route your +5v line into the board. I'll use the metal housing of the sim card reader to attach the ground.

hxxp://i.imgur.com/koag4.png

Since the back of the phone is metal and its always going to be in a case I'm going to have to use pogo plugs or some other form of metal contacts to go through the back housing to allow me to pull off the case/back whenever I need. I'll have my charge port free to use over USB as well