I found some useful guides on using a USB flash card reader under Linux. I had already compiled the modules in case I ever needed them, so I merely had to stick my flash card in. My reader supports four types, but I didn’t enable SCSI support to probe multiple LUNs, so only the first is visible. Fortunately, it’s also my FC reader, so I’m good. I can’t imagine I’ll ever need to read SDs.
One odd thing I found was, apparently, my card is formatted as FAT12. A few additional arguments to mount were necessary.
# mount -t vfat -ofat=12,umask=000 /dev/sdb1 /mnt