GRUB boot disks without GRUB preinstalled
 

I want to create a bootable flash drive for memtest86 for my laptop and desktop PCs, but the GRUB files on my desktop are compiled for a 64-bit system, the laptop is 32-bit, and I still can't install GRUB on the laptop (can't figure out what is blocking the MBR, Vista or Mcafee anti-virus).

I'd prefer doing it from source code, having nothing do to with the Hard Disk.

You can run memtest from a live cd. If you can not boot your usb or a cd then I would not know how to without putting something on the hd.

Any GRUB developers here?

I was not aware that GRUB could be compiled for 64-bit vs 32-bit (or why it would matter)....but, regardless: Are you saying that you cannot install GRUB to the MBR using the GRUB shell method?
grub
root (hdx,y)
setup (hdx)

What happens if you do this? I would have assumed that the grub shell uses a low-level utility (like dd, for example) and that it could not be "blocked".