I'm having this same problem. Downloaded 0.8.4 on my hackintoshed mini9, formatted the drive that previously held 0.8.3 (again, on the mini9), and NetbookMaker doesn't see the drive, though disk utility does.
putting the SL install image onto this flash drive - I have another, larger, flash drive that I used to hackintosh the 9 that I'll be using for my 10v.
I've tried formatting several times, changing the boot type from GUID to MBR and back again...no difference. NBM refuses to acknowledge that there's a flash drive attached.
Any suggestions? I was looking forward to doing the NBI method #1 for the 10v, but if I can't get this resolved, I'll be doing method #2, and with an older version of NBM.