Using any random quad-SPI programmer and soldering it to the chip that contains your BIOS. If dragosr is suspecting a BIOS malware, I can't understand that he hasn't done that yet. From what I've read on his Twitter and Facebook account, he would have spent 3 years investigating this malware and is just now thinking of dumping the ROM of his "infected" USB devices.
Smells fishy to me.