1)prepare a free partition with beos format (the size >= beos.iso (or image.be) file size ) ,
2)boot into you linux system , login as root ,
3)uncompress your beos zip ball , you will get a *.iso file .
(you can also use your image.be file .When you install beos5 pe in M$ windows ,you can get it in your BEOS path )
4)now pls use "dd" command to write your iso (or *.be) file to the partition
dd if=*.iso of=/dev/hdXY bs=xxxK
In your beos path , there is a floppy.img (i can't remember the file name, sorry)
You can copy it to your /boot/grub/ , edit your grub.conf
reboot your box , select beos , hit [Enter] , press [space] to call beos boot menu,
from the menu your can select to boot your beos which has been installed
in M$ windows.