Hi KA,
there is no difference on Cat6509 switch... you configure the 3 switches in HSRP, 1 will be active, the second will be standby and the third will stay in listening mode and will move to a different status if one of the other 2 disappears.
HSRP is meant to give full redundancy for 2 routers only, the third is in a kind of 'cold mode'.
No particular site to show as the config is exactly the same for any other IOS based router.
Riccardo