You can use the script like this:
wget https://bitbucket.org/tkoskine/avr-ada-build-script/get/tip.zip unzip tip.zip cd tkoskine-avr-ada-build-script-1677e4b66123 sh -x build-avr-ada-environment.sh
The script will build GNAT 4.7.0 into $HOME/programs64/gnat-native-470 directory and AVR-Ada and AVR-GNAT into $HOME/programs64/avr-ada-470 directory. If you want to change the locations, you need to edit GNATPREFIX and AVRADAPREFIX variables at the beginning of the script.
The script is tested on Fedora 16 and Fedora 17, although I make no promises that it actually works anywhere.