reading non-standard floppy formats

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

Is there a saner way of reading non-standard (e.g., 10 sectors per track) 
floppies than either
a) building a custom kernel with modified fd_types in sys/dev/isa/fd.c
b) writing a user-space program that sets the appropriate parameters with 
FDIOCSETFORMAT and then, holding the device open, writes the raw floppy data to 
a file?

I first thought that letting fdformat(1) sitting at the confirmation prompt 
would do the trick. But fd.c explicitly catches a second open with modified 
sc_type.

I must be missing something. How am I supposed to use a floppy I fdformat(1)ted 
with a non-standard geometry?