I suppose you could try to install grub or unetbootin and set the boot options to the proper partitions on the flash drive. Then change the boot order in your bios. You will also need to use the windows 7 install disk to fixboot and fixmbr. This may or may not even work.
If the flash drive is plugged into another computer their bios will need to be set to boot to usb first in order for it to even display the boot options on the flash drive. And the partition scheme will be different so it will not matter if it does boot to the flash drive.
Although I don't know why you would want to do any of this.