I recently got a PILBox and after some struggle managed to get it working together with Mac OS X!
ILPER 1.35.2 for Linux built without any problems on my office x86 Mac OS X laptop. Then I used FTDI VCP driver for Mac OS X and the strange device /dev/cu.usbserial-FTFWKSK7 (as the other plausible device names just hung when the device was opened).
With this setup, I started emulation in ilper and wrote the contents of my HP-41 to the simulated mass storage device, it just worked!
And this on native Mac OS X, I am so happy!!!
I have a feeling that it is a bit slower than a floppy drive? I have not measured, but I think the hardware is quicker, though maybe I am fooled by the floppy drive making entertaining sounds while the PILBox is just.. quiet.
Thank you Jean-Francois Garnier and Christophe Gottheimer!