To install Instinctiv Shuffle you should have a 1.1.4 Jailbroken iPhone or iPod touch. You can find a great tutorial on jailbreaking your iPhone here
Press to launch Installer from your Springboard.
Press to select the Install tab from the bottom of the screen.
Press to select Multimedia from the list of Categories.
Press to select Instinctiv Shuffle from the list of Packages.
Press the Install button at the top right of the screen
Press the large Install button that appears
After installation is complete you will be returned to the Categories list. Press the Home button to return to your Springboard. Notice the new Shuffle icon. Press to launch it!
Move the Smart Shuffle switch to the ON position
Using Instinctiv Shuffle
You will now notice that the Shuffle option in your iPod has been changed to Instinctiv Shuffle. Press to select this option and and let Instinctiv Shuffle attempt to determine the music you would like to hear!