I believe the intent of LPP is to use decaborane, B10H14, which is a solid at STP that sublimates into gas at a moderate vacuum. It is nasty stuff, though, as it is a neurotoxin. You really don’t want to handle it if you don’t know what you’re doing.
I do not mind the procedure, I would be happy to have any source of boron hydride compound, it would be better using B11, not natural boron, because neutronicity increasing