D.I.Y. Photek Softlighter II Flash Bracket

I picked up a couple of Light Mods recently - the Photek Softlighter II in both 36" and 46" sizes. They are basically a bounce-umbrella with a diffuser panel to soften the light and give you more control over spill. The diffuser has a "sock" over a hole in the center that you put your flash through and then it's all good. The only problem is, with a standard umbrella bracket setup, your flash is going to be pointing  anywhere but at the center of this thing. I looked around but didn't find anything I could buy to fix this.
So, I went to the hardware store instead: