there are simpler ways (use the mount offset option) to do this but this is the way I am used to.
sudo losetup -o 80740352 /dev/loop0 debian6-17-02-2012.img
sudo mkdir /mnt/debrootfs
sudo mount /dev/loop0 /media/debrootfs
then use your favourite method to copy whole directory trees of files from one place to another to copy all the files and dirs in debrootfs to a directory in $HOME/raspberry_pi_development
sudo chown -R raspberry raspi_debian/*
sudo chgrp -R raspberry raspi_debian/*
sudo chmod -R 777 raspi_debian/*
sb2-init raspberry_deb $HOME/raspberry_pi_development/arm-2011.03/bin/arm-none-linux-gnueabi-gcc
and that's pretty much it.