Another way to look at the issue is to remember that the reference is arbitrary, and what matters is the angle of the wing, horizontal tail, and engine in realation to each other.

So, you could set your airplane on a table, and hook up a meter to your horizontal stab and observe a "+5". Then check your wing. If it also reads "+5", then you've got 0 differnece between the two, and you're good to go if the kit calls for "0". Now check the engine, and see what it's doing compared to the first two. If someone says they use 0, 0 on the wing and stab and -1 on the engine, just make sure the engine shows one degree less than the others, and you're good to go.