First determine what version of EEPC you're using - 6.2 is very old. The recovery options are different depending on version.
Looks like EEPC 7.0.1 or 7.1.1 are being used (I think 7.1.1 in my case). So yes, I had the incorrect guide. But looking at the EETech guide for 7.0, I don't see any relevant differences.
Does the emergency boot sound like the correct way to go?
Most likely yes - I am assuming you're the IT department for this machine - because you're going to need the keys to be exported from EPO before you can do this.
Can any harm result from attempting to emergency boot an SED/Opal drive with non-Opal EETech? I'm not sure if my drive is SED or not.
I am stuck with the exact problem as that of yours. And have exactly same set of Questions as that of yours..
Did you manage to recover your data back ? Its Yes, how ? by Overwriting the MBR ? Safe Boot ? or a Long time decrypting Hard Drive ?