If you are talking about your new Pompino Steve, the OLN (over lock nut - distance - or the gap between your rear fork ends left and right, where the axle sits ) should be 120mm (stick a ruler in there with the wheel out to check).
I had the hubs for my Pomp made for me by BETD Ltd - Goldtec track hubs.
For some reason the OLN on older pomp frames (mine) is 135mm - but it was easy enough for BETD to make up spacers and a longer axle to match this.
However, the axle which I have from them, will only accept bolts - whether they're hex (for a spanner) or cap (for an allen key) head.
I'm sure they could make you an axle to accept nuts, but you'd need to talk to them about that.
Give Dan a call on 01782 629462.
ETA - Plucky's solution may be the easier way to get what you are after, and certainly nowhere near as spendy as BETD.