try this
title Start Hiren's BootCD
find --set-root /HBCD/boot.gz
map --mem /HBCD/boot.gz (fd0)
map --hook
chainloader (fd0)+1
rootnoverify (fd0)
map --floppies=1
boot
/HBCD/ is the directory where I have it, in your case I guess it should be
/systems/Hirens/HBCD/boot.gz