I am researching this very thing at the mo, seems no one does a VSS fitting for a T5, but that's not to say that there isn't one.
The problem is there are over 260 versions currently of the T5, even the SSANG YONG Musso & Korando used a version!!, as well of course as GM, FORD, to name a few.
I am sure that eventually I will track one down that will fit straight in, failing that I'll see about making one , the VSS is only around £30, and shouldn't be too hard to graft on.
I'm doing this as going lecky speedo(smiths telemetrix), TVR when using this box used a sensor on the diff casing to read the ouput from shaft, I assume they would have researched this to see if there was a drop in VSS for the T5, but you never know.
You can get units that convert from one count to another, so in your case if push came to shove could always use this reading off the diff outpout etc, converted into your pulses per mile of the oe sensor you have.
tabetha