How do I read/write (program) the MBR/VBR of a flash drive?

I'm looking for a method of reading/writing (actually programming) the Master Boot Record (or maybe VBR) of a usb mass storage device. Actually its a flash drive whose MBR I want to program, so that whenever I plug it into any computer, a program (stored on my flash drive in a file) gets executed.

I know quite a bit of assembly but I don't know h开发者_开发百科ow to go about programming MBRs.. Please help

Thanks

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If you're using linux, you can simple open the device file /dev/sdXY and write to it, the MBR will be the first 512 bytes.