spektro, muito legal, vou te dar umas dicas por onde começar..
Meu site favorito para desenvolvimento é este:
http://iphonedevdocs.com/index.php , lá você pode encontrar bastante referencia, inclusive um hello world pra treinar a compilaçao.
Mas..
Voce tem que começar por insalar o toolchain em um Mac OS X
Isto significa instalar o compilador em C para as bibliotecas do processador ARM do iPhone. Assim vc pode começar a programar.
O Dev Team criou o toolchain, infelizmente o wiki deles saiu do ar, porém existem outras fontes.
Já vi gente que conseguiu instalar o toolchain pelo Cygwin (
http://wiki.iphonegameover.com/Windows_ ... stallation), mas eu não recomendo... Arrume um Mac com o Leopard

Bom aqui vai o caminho das pedras para criar o compilador, eu tenho ele criado no meu Mac OS por esse guia e funciona:
Entretanto existem outros (
http://george.zjlotto.com/index.php/iphone-toolchain/)
Um que recomendo dar uma olhada é este também:
http://code.google.com/p/iphone-dev/wiki/Building- Código: Selecionar tudo
HOWTO build the toolchain for 1.1.1 on Leopard
by drudge with pure ownage by lupinglade
Ensure that you have a copy of bison and flex installed on your system. All major systems should
have these tools installed or available in package management systems.
$ bison --version
GNU Bison version 1.28
$ flex --version
flex version 2.5.4
Check out a copy of LLVM SVN, and build a release build (as opposed to a debug one). Currently, due
to Issue 70, we are limited to revision 42498.
svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm-svn -r 42498
pushd llvm-svn
./configure --enable-optimized
make ENABLE_OPTIMIZED=1
sudo make install
LLVMOBJDIR=`pwd`
popd
Check out a copy of the iphone-dev SVN repository.
svn checkout http://iphone-dev.googlecode.com/svn/trunk/ iphone-dev
pushd iphone-dev
Make a directory to hold the toolchain.
sudo mkdir /usr/local/arm-apple-darwin
Build odcctools.
mkdir -p build/odcctools
pushd build/odcctools
../../odcctools/configure --target=arm-apple-darwin --disable-ld64
export INCPRIVEXT="-isysroot /Developer/SDKs/MacOSX10.4u.sdk"
make
sudo make install
popd
Get a copy of the iPhone root filesystem. This is usually obtained by decrypting and extracting the
iPhone restore software using these tools, but there are many other methods to obtain this,
including simply using scp to download all the files from the iPhone over Wi-Fi. I would use the method
describled here: http://www.touchdev.net/wiki/Jailbreak_Guide to get the dmg.
To unpack the root filesystem, mount the dmg, open terminal and run
sudo mkdir /usr/local/share/iphone-filesystem
sudo cp -Rp /Volumes/Snowbird3A110a.N45Bundle/* /usr/local/share/iphone-filesystem/
Now, set the environment variable $HEAVENLY to its path:
HEAVENLY=/usr/local/share/iphone-filesystem
Patch the system headers
pushd include
./configure --with-macosx-sdk=/Developer/SDKs/MacOSX10.4u.sdk
sudo bash install-headers.sh
popd
Install csu, which includes crt1.o, dylib1.o, and bundle1.o. Don't rebuild them from source, as this
requires a working cross-GCC, which you don't have yet (and the build-from-source process for csu is
broken right now anyway). Binaries are provided for this reason.
mkdir -p build/csu
pushd build/csu
../../csu/configure --host=arm-apple-darwin
sudo make install
popd
Configure and make LLVM-GCC. Make sure that $LLVMOBJDIR and $HEAVENLY are set per the instructions
above.
mv llvm-gcc-4.0-iphone/configure llvm-gcc-4.0-iphone/configure.old
sed 's/^FLAGS_FOR_TARGET=$/FLAGS_FOR_TARGET=${FLAGS_FOR_TARGET-}/g' \ llvm-gcc-4.0-iphone/configure.old > llvm-gcc-4.0-iphone/configure
sudo ln -s /usr/local/arm-apple-darwin/lib/crt1.o \/usr/local/arm-apple-darwin/lib/crt1.10.5.o
mkdir -p build/llvm-gcc-4.0-iphone
pushd build/llvm-gcc-4.0-iphone
export FLAGS_FOR_TARGET="-mmacosx-version-min=10.1"
../../llvm-gcc-4.0-iphone/configure --enable-llvm=`llvm-config --obj-root` \
--enable-languages=c,c++,objc,obj-c++ --target=arm-apple-darwin --enable-sjlj-exceptions \
--with-heavenly=$HEAVENLY --with-as=/usr/local/bin/arm-apple-darwin-as \
--with-ld=/usr/local/bin/arm-apple-darwin-ld
make LLVM_VERSION_INFO=2.0-svn-iphone-dev-0.3-svn
sudo make install
popd
popd
You're done. Have fun!
De uma olhada no blog do Geohot também, ele da bastante dicas de engenharia reversa e de como desbloquear através de truques "divertidos" de escrita em endereços de memória. O anySIM 1.1 é opensource pra vc dar uma olhada também.
[]s