tell grub its base directory

[Harry Putnam]

Current cvs grub apparently does not have a specific command to tell
grub where to look for its files in general.

If there is such a command it is well hidden.

On openbsd, the os installs a file at /boot.  Not a directory but a
file.  I'm not sure what this is or does but unless removed it means
the defauilt /boot/grub will be a non-starter.

How can I tell grub to look in /grub_boot for:
  grub.conf
  images 
  map 
  etc

I see ways to point to those specifically but no command line switch
to point to a user defined base directory.