As you probably already know, you can effectively "block" the upward movement of the strat-style tremolo by simply tightening the springs. The tension will pull the tremolo back forcing it against the wood of the guitar.
To "block" a Floyd Rose floating trem, you must insert a wood block (of proper height) under the tremolo system to restrict any upward movement of the tremolo system. You want to then tighten the springs so that the tremolo is no longer 'floating' on the fulcrum, but rather is forced to rest upon the block of wood.
This will allow you more freedom with alternate tunings and you can also rest your hand on the bridge without forcing the guitar out of tune. You can depress the whammy bar and have the strings slacken, and when you let go of the bar, the springs will pull the tremolo bridge back to rest against the block of wood.
Floyd Rose locking tremolo systems are a unique tool. Most people either love 'em or hate 'em. Personally, I am not comfortable with blocked bridges. I prefer them to float because I don't like the stiff feeling of the whammy bar 'thunking' against the guitar's body when I let go of the bar.
You might also consider trying out the
Hipshot Tremsetter. This inexpensive gizmo effectively simulates "blocking" your floating system. It allows you to depress the whammy bar to slacken the strings, but restricts you from pulling up on the bar. Not my cup o' tea, but some guys like it.