Here is the first doc to read in order to build your own image.
for more information, tuxbox-wiki is your friend ;)

# $Revision: 1.31 $
# This document describes the steps needed to set up a cross compile
# environment (CDK) for linux on embedded PowerPC using a GNU system.
# Copyright (c) 2002-2004 Andreas Oberritter <obi@tuxbox.org>
# Permission is granted to copy, distribute and/or modify this document
# under the terms of the GNU Free Documentation License, Version 1.2
# or any later version published by the Free Software Foundation;
# with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
# A copy of the license is included in cdk/common-licenses/FDL-1.2
# This document is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of

I. Prerequistes:

- cvs
- autoconf >= 2.57a
- automake >= 1.8
- libtool >= 1.4.2
- gettext >= 0.12.1
- make >= 3.79
- tar
- bunzip2 (bzip2)
- gunzip (gzip)
- patch
- infocmp (ncurses-bin / ncurses-devel)
- gcc 2.95 or >= 3.0
- g++ 2.95 or >= 3.0
- flex
- bison
- pkg-config
- wget
- libpng2 or libpng3 (DirectFB)
- zlib (development headers)

Ensure that you have these programs installed and accessible on your system.
Compare version numbers where applicable. Don't report any bugs before having
verified that you are using the correct versions.

II. Getting the sources:

- It is recommended to add a new user to your system, to prevent data loss.
If you do not have sufficient rights to do so, remember that everything
you do happens at your own risk. Do never build as root. Don't even think
of it! It will make your system go nuts and eat your cat!

- Login as the desired user.

- Enter the following commands:

you@pc:~$ mkdir $HOME/tuxbox-cvs
you@pc:~$ cd $HOME/tuxbox-cvs
you@pc:~/tuxbox-cvs$ export CVS_RSH=ssh
you@pc:~/tuxbox-cvs$ cvs -danoncvs@cvs.tuxbox.org:/cvs/tuxbox -z3 co -P .
anoncvs@cvs.tuxbox.org's password: anoncvs

Note: There is a dot at the end of the cvs command line
and, yes, it actually belongs to the command.

- Remember that you do not ever have to fetch the complete cvs tree again,
if you don't delete it. You can update the tree by typing:

you@pc:~/tuxbox-cvs$ export CVS_RSH=ssh
you@pc:~/tuxbox-cvs$ cvs -danoncvs@cvs.tuxbox.org:/cvs/tuxbox -z3 up -dP
anoncvs@cvs.tuxbox.org's password: anoncvs

Please do that, even if you have a broadband internet connection, to
reduce our traffic costs. Thank you!

III. Generating the Makefiles:

- Enter the following commands:

you@pc:~/tuxbox-cvs$ cd cdk
you@pc:~/tuxbox-cvs/cdk$ ./autogen.sh
you@pc:~/tuxbox-cvs/cdk$ ./configure --enable-maintainer-mode \
--prefix=$HOME/dbox2 \

IV. Building the CDK:

- Enter the following command (see Makefile.am for other make targets):

you@pc:~/tuxbox-cvs/cdk$ make all

- This step should always complete without errors. If it does not then please
report at https://tuxbox.org/forum/

- If you want to try building additional programs which are usually not
needed for using tuxbox applications, then enter

you@pc:~/tuxbox-cvs/cdk$ make extra

- These programs are hardly maintained, so they might sometimes fail to
build. If you encounter errors, then please report them to the address
mentioned above, but do not expect to get the problems fixed quickly if you
do not provide a solution to the problem.

- Note that you can skip single make targets by typing

you@pc:~/tuxbox-cvs/cdk$ touch .deps/package_name

for more informations about options, packages and installation instructions, take a look at
B. Regards