Yoodoo,
Do us a favor, cut and paste your terminal commands starting with
'diskutil list' into a code window.
Its dangerous answering your question without seeing your exact setup in this case. (we are mucking about with boot sectors afterall....)
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I assume that when you say
...I get to the step where I type:
That you were able to erase and mount the EFI partition normally, your terminal paste will give us the information we need to better assist you.
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I will let you know when trying to go to a USB stick, I had some issues as well, but they boiled down to writing the correct file system to the boot partition and getting it mounted before attempting dd commands.
lastly, how big is your USB drive? (silly question probably, but you have to check everything...)
S_L