[OS X TeX] Flasmode and XeTeXinputencoding

[seroul at math.u-strasbg.fr]

The following file works perfectly with XeTeX (TeXShop 2.18)
on a PowerBook (OS X 10.5) :



% !TEX TS-program =  xetex
% !TEX encoding =  utf8

\XeTeXinputencoding mac

\font \toto = Palatino at 10pt

\toto

Ce théorème élémentaire est
extrêmement simple à prouver.

\bye




But when I try to use Flashmode, I get an error :


This is pdfTeXk, Version 3.1415926-1.40.9 (Web2C 7.5.7)  
(format=pdfetex 2008.10.20)  21 OCT 2008 16:28
entering extended mode
\write18 enabled.
  %&-line parsing enabled.
**essai-xetex-mac.tex
(./essai-xetex-mac.tex
! Undefined control sequence.
l.5 \XeTeXinputencoding
                         mac
?
! Emergency stop.
l.5 \XeTeXinputencoding
                         mac
End of file on the terminal!

!  ==> Fatal error occurred, no output PDF file produced!

What can I do ?

Thanks.

Raymond Séroul