From what I remember, it's a fairly simple in-line resistor to reduce the voltage, but the silver-oxide batteries have a surprisingly flat discharge voltage anyway, rivaling that of mercury.
If you're shooting B&W negative, I'm sure you could get results 'close enough for government work' shooting at the rated speed. After a few rolls, if you notice consistent over-exposure that is problematic (I've come to appreciate a touch of overexposure in my negs), a simple adjustment of ISO on camera would probably be sufficient.
Of course, it's worth noting that eventually, I'm planning on sending in my own QL17 for a CLA soon, at which point, I'll be having the shop convert it for the silver-oxide cells...so take that for what you will. :P