Just spoke to Mr WR. Regarding the alcantara it does have two directions. The material itself consists of small particles, I don/t know how to name them in english. Anyway, there is lets say downstream and upstream direction that affects the light and hence the appearance i.e. the color of material. That is something to be taken care of when doing a seat, especially if you are joining two or more parts together. But, on steering wheel it is pointless since it will cover the wheel in circular form and hence there will always be a section that is in 'right' and 'wrong' direction at the same time.
So, to cut a long story short: for retrimming the steering wheel only the sq. cms count! As long as you can provide him with ENOUGH material to cover the 3 and 9 o'clock sections (the handles) he can and will do it.
I hope to find enough time today to take a photo of pattern needed that will post here and from that you can calculate whether you have enough material
Cheers,