Nothing special in the setup. You just tell your Z68 board to use the SSD drive as cache and it does it for you.
But the price between a cache only 32GB SSD $70
and a full boot drive 64GB SSD $110
isn't that huge. When you look at the price it turns out you'd end up being better off just saving up for a SSD boot drive and adding it later.
And anything you can add later helps keep the total price down now.