make sure its the 15m bleep test you download as most on the web are for the 20m test and are not labelled. You can use the 20m to practice but the bleeps are at different speeds so does not give an accurate reflection.
It can't be done on a treadmill (even if you could programme it ) as it can't simulate the turns.
for some reason it is exremley hard to get them in 2E width size, I got 2 pairs from the states via ebay and 1 pair from their outlet shop in Shap. I contatced NB and they said they don't have much demand for the 900 range in the 2E width in the UK!
I have a pair of 903s coming from the states in 2 E