Adjusting power output on laser module

[outsider]

What's the recommended method of adjusting the power on the typical 3v laser modules (12x30 or 6x10).

I want to set it up so that I have full power or 1/2 power controlled by a switch.
Is it easy to hack the modules? Is it as simple as a resistor change?

 

[Gadget]

Should be as simple as adding a 3-position switch with a resistor on one of the positions to half the power.

-G

 

[outsider]

I don't think it's quite as easy as lowering the voltage (by sticking a resistor in series, is it?
It's the current that needs to be varied to dim an LED, or am I incorrect?

 

[The Lightning Stalker]

Depends on the module. Some of them are
nothing more than a resistor to begin with.