Are you suggesting he physically turn a projector on it's side?
Every projector I used was designed for max air flow to ventilate the
extraordinary amount of heat they generate. I don't remember ever seeing a
projector built to be rotated in place. That sounds like a good way to brick
the unit.
I'm saying that is the only way he is going to get a "portrait mode" out
of a projector. Just like a screen, a projector has a physical array of
liquid crystals. You can't just electronically tell a projector to change
the physical arrangement of those crystals. There just might be some
really high end models of projectors that do one of the following:
* Mechanically rotate the array on command.
* Use a square array of the maximum size needed then only use the band of
pixels in the middle needed to display the desired ratio.
* Optically rotate the display using mirrors in the projector.
I seriously doubt a single manufacturer spends the money to put into a
product these extra features that will almost never be used.
If you want to rotate the projector it is possible to do so without
blocking the vents, though it may take a bit of ingenuity. The air is
pushed through by a fan so gravity will not affect the cooling
efficiency. Most of the projectors at my university are mounted hanging
upside-down from the ceiling so you can see and reach the buttons. Some
projectors even have a plate in the bottom for bolting onto a plate which
has been welded onto the end of a pipe or other mounting apparatus. If
that mounting apparatus were hinged then the projector could easily be
rotated 90 degrees simply by swinging the apparatus on its hinge.
There are 1001 different ways this could be achieved. However, unless the
original poster has lots of time or political pull I doubt anyone would
be willing to do any of them.
What I recommend is that the original poster simply accept the fact that
there are limits to what one can do in the real world and stop trying to
project a Tablet PC screen in portrait mode. Just put the thing back into
standard landscape mode and write on it that way when he is projecting
onto a screen.