Without listing a hub and rim, it'll be impossible to tell what length spokes you'll need to get. And, yes, I use a 4x 36, front and back, although I didn't lace it myself (why bother if Empire will do it for me for free?).
I could probably find the innerdiameter of the BFRs pretty easily, but I've never even heard of Bulletproof hubs. Try calling Albes up and asking them what spoke length you'd need, they'd be more likely to know.