How do I get /dev entries for removeable media to appear when inserted?

[Darren Pilgrim]

I have a zip drive (afd0).  At boot, the only afd0* device is afd0, which makes
it rather difficult to mount MSDOS formatted disks.  I can get the device
entries to appear by issuing `mount /dev/afd0 /mnt`, but it's annoying to have
to do this.  Is there a way to cause this update automatically, or to force the
existance of device nodes for slices and partitions?

This is on 5.0-R.