[Dev-luatex] How to build LuaTeX format files?

[Nicola]

Hi,
sorry for the silly question, but... how do you generate the desired 
formats after installing luatex? I've tried with

luatex -ini luatex.ini dump

and I get

This is LuaTeX, Version beta-0.40.6-2009062619 (Web2C 2009) (INITEX)
(/usr/local/texlive/2008/texmf-dist/tex/plain/config/luatex.ini
(/usr/local/texlive/2008/texmf-dist/tex/plain/config/etex.ini
(/usr/local/texlive/2008/texmf-dist/tex/plain/etex/etex.src

! e-TeX  fatal error: this file can be processed only in extended mode;
  did you perhaps forget the asterisk?

luatex -ini lualatex.ini

This is LuaTeX, Version beta-0.40.6-2009062619 (Web2C 2009) (INITEX)
(/usr/local/texlive/2008/texmf-dist/tex/latex/latexconfig/lualatex.ini
(/usr/local/texlive/2008/texmf-config/tex/generic/config/pdftexconfig.tex
! Undefined control sequence.
l.3 \pdfoutput
              =1
? 

With fmtutil I had no more luck... Help?

Regards,
Nicola

PS for Taco: I think that adding the needed commands to the INSTALL file 
would help a lot (also for MetaPost) people like me, who are neither 
beginners nor tex live gurus.