Here's the method I used to do it:
On a Linux system:
timeout=10 default=0 title FreeDOS kernel /path/to/tftp/download/area/memdisk initrd /path/to/tftp/download/area/freedos-boot-fd.img
You should now be ready to boot your client. Assuming the boot is successful, you should get the "grub" boot menu. Select FreeDOS and hit return.
you should see:
Welcome to the FreeDOS MetaKern boot menu Please type a digit to select a list item or type A or C to reboot from A: or C:... Using <1> if no choice after 10s. Boot sectors: 1 -> FreeDOS (speedup, 386+) 2 -> FreeDOS (chain to kernel .sys!)Hit "2" here.
Now you should see:
FreeDOS Beta9 ServiceRelease1 (2004-November-30) INSTALLATION 1. Install to harddisk using FreeDOS SETUP (default) 2. FreeDOS Safe Mode (skip driver loading) 9. Run setup with user-specified storage driver(s) Enter a choice: 
Hit "2" here too. You should have an "A:\>" prompt. Go to whereever you put your flash program and image and flash BIOS.