a. Decide were your tools and your sdk are going to be ;-)

 For example:
  /works/devel/ps2/tools
  /works/devel/ps2/sdk

b. First we need the tools, let's get them started with svn...

svn co svn://svn.ps2dev.org/ps2/trunk/ps2toolchain

c. ...and build them using toolchain.sh!

Make sure that you have the correct env settings

For me:

 export PS2DEV=/works/devel/ps2/tools
 export PATH=$PATH:$PS2DEV/bin
 export PATH=$PATH:$PS2DEV/ee/bin
 export PATH=$PATH:$PS2DEV/iop/bin
 export PATH=$PATH:$PS2DEV/dvp/bin
 export PS2SDK=/works/devel/ps2/sdk
 export PATH=$PATH:$PS2SDK/bin

You will need them in the future too (not only to create the tools) so you might want to add them to your profile.

Note: the script will download the needed sources from the net. As of right now, the ps2 port won't compile with the most recent versions of the toolchain so you will have to modify the scripts "005-ps2sdk.sh" and "006-ps2client.sh" to svn check out revision 1628 or earlier.

You won't need most of "ps2toolchain" after building but be sure to save the ps2sdk source (from ps2toolchain/build/ps2sdk) because some other libs (eg. SjPcm) rely on it. I suggest keeping it in /works/devel/ps2/sdk and export:

export PS2SDKSRC=/works/devel/ps2/sdk-src

d. Nearly there! Now we still need some extra libs which are not provided with default SDK:

- I suggest storing all of them in "sdk-extra" so that you just need to edit one line in Makefile.ps2 to compile scummvm

- you can call it "sdk-ports" if you want to be consistent with svn naming structures

    // zlib
    svn co svn://svn.ps2dev.org/ps2/trunk/ps2sdk-ports/zlib
    cd zlib
    make

    // libmad
    svn co svn://svn.ps2dev.org/ps2/trunk/ps2sdk-ports/libmad
    cd libmad
    mkdir ee/lib
    make

    // sjcpm & tremor
    [ the porter will have to provide these as they are specially optimized versions for the PS2
      You can contact him at sunmax@libero.it]

e. get scummvm

svn co https://scummvm.svn.sourceforge.net/svnroot/scummvm/scummvm/trunk trunk

-or-

svn co https://scummvm.svn.sourceforge.net/svnroot/scummvm/scummvm/branches/branch-1-0-0

cd trunk/backends/platform/ps2

edit Makefile.ps2 to match your sdk-extra (for example: PS2_EXTRA = /works/devel/ps2/sdk-extra)

make -f Makefile.ps2

Your fresh-baked scummvm will be waiting for you in elf/scummvm.elf ;-) If you don't need the symbols, just strip them ee-strip --strip-all scummvm.elf

enjoy!