My first attempt to create boot disks has failed.
I installed FreeDOS in a VirtualBox guest, and connected a USB floppy drive to my Windows host. The good news is that Windows was able to format the disk, so it seems good. Also, the FreeDOS guest was able to read the floppy.
Unfortunately, it was not able to write to the disk: it gives a "FATAL: int13_diskette_function: write error" error when trying to do a FORMAT A:.
I think the next thing I am going to try is to connect a USB-> PATA adapter to my laptop drive, have a VM boot the OS/2 install disks, and see if I can get the installer to install to the laptop drive.