[Coco] double-sided floppy setup in OS-9

[Chad H]

I'm wondering if someone can get me started or point me in the right
direction on this.  I've been predominately a DECB user but have had OS-9
for a long time, just never really gotten into it.  I would like start
learning more about it but one thing bugging me is my floppy drive access.
Currently I have 2 x 5.25 Double sided 5.25 floppies in my FD-502 enclosure.
I'm using modified DECB EPROM to access them as 0,1 for top drive and 2,3
for bottom drive.  When I load OS-9, it exhibits the same problem as DECB
used to, can only seem to access one side of one drive.  I've heard there is
some sort of device descriptor files or something that needs set but I have
no idea how to go about doing it.