Edit:
We have now a temporary git repository at gitorious:
http://gitorious.org/replicant

Before starting * root your phone * Backup your current system!!! Build system
Let's say that our build directory is ~/replicant

Check out the Dream Android repository : {{{
mkdir bin
cd bin
curl http://android.git.kernel.org/repo >~/bin/repo
chmod a+x repo
cd ..
mkdir replicant
cd replicant
../bin/repo init -u git://gitorious.org/replicant/manifest.git
../bin/repo sync
}}}

Build process: {{{
TARGET_PRODUCT := htc_dream
}}}
To ~/replicant/buildspec.mk * Then type {{{
cd ~/replicant
export ANDROID_JAVA_HOME=$JAVA_HOME
make
}}} * The files to flash are in ~/replicant/out/target/product/dream,flash them and then clear the cache * boot and push the wifi firmware if you want it

Status * ril works more or less: * * calls should work(in/out) * * sms should work(in/out) * * hearphones not supported * sound works even with headphones(beware calls's sound don't work with headphones)