Here are instructions for getting ShairPort installed on your 10.6 64bit machine.
These are modified instructions from: http://asktherelic.com/2011/04/11/air-speakers-for-everyone/
Finally use your COMPUTER as an AirTunes speaker!!!
brew install pkg-config libao
ARCHFLAGS="-arch i386 -arch x86_64" perl -MCPAN -e 'install Crypt::OpenSSL::RSA'
git clone https://github.com/albertz/shairport
cd shairport
make
perl shairport.pl should have you running!
Edit the shairport.pl file to edit the name, otherwise it's advertised as a horrible name like "shairport on 68832 mac..." blegh. Give that thing a clean name and stay classy.