To install the theme engine extract it to somewhere convenient and in that directory,
run: "./configure --prefix=/usr" then "make"
For animation support add "-enable-animation" when running "./configure"
Then as a root user "make install".
Then install the gtkrc themes by extracting them to your ~/.themes directory (3 themes in total).
To change your current theme to Aurora (under GNOME) open up Theme Preferences (usually somewhere under System > Preferences) click the Customize button and under the controls tab select the theme you want.