Get the instrument with the loops up in the Giga editor.
In the sample pool window right click on the loop, or folder containing the loops.
You should get an option to export sample or export sample directory. (I think you set the directory in the editor preferences).
When you export loops, they are exported as wav files.
Now just load up Acid, navigate to the directory with your Giga samples, pull the wavs into Acid, adjust their properties (number of beats, loop type, etc), and you can adjust tempo and pitch independently in the programme