I really thought I had a no-solder solution for the trigger, but if the Alltel cable is unavailable, well, that's hardly a solution.
Are you at all willing to try splicing two cables to make a new one? If so, I will make a video showing you what to do. Even after buying a second USB cable, a cheapy soldering iron, and a bit of solder, it will be cheaper than the splitter solution.
If you are not comfortable with that, I've looked on eBay, Google, and elsewhere. Have you tried asking if someone has an extra in the StereoDataMaker Yahoo Group?
I used to sell triggers, but I am done doing that. I really don't enjoy it and I'm about to pack up my workshop.
You might also be able to get away with some kludge of cables and gender changers. I'm thinking a cable like this
And a gender changer on the end like this
and then two ordinary A to Mini-B cables