I have to go along with those who say a presentation just won't do
it. They are waaayyy too easily dismissed in these cases.
My ultimate plan for those situations when I'm not allowed to
consider simple physical violence runs along these lines
1. I test people who are not Them, but who are accepted by Them as
being intelligent consumers of software.
2. I get an actual list of people who the engineers will admit fall
into the category of Intelligent People.
3. I get them to provide a venue with cameras, video feeds from the
screen, and one-way observation.
4. I make them watch while a few people they consider smart fail to
use the software as they would have themselves.
5. If they say, well, those testers weren't the target user group, I
repeat the process, this time getting them to agree to a description
of their target user (I once had a group that insisted repeatedly and
in the same conversation that their target user was a total novice
user who could create a dynamic website from scratch...It helps to
write each element down, so that they can recognize their
discrepancies), and getting their buy-in on the fit of each potential
tester to the target user description.
I generally don't try to be nice to the engineers. Yes, they may
reject what I have to say, but they can't pretend I didn't say it,
and I find that's a much more frequent problem.
User Experience Consultant