you do it like this:

function testfunc(_variable)
{
temp = _variable;
}

or for arrays:

function testfunc2(&array)
{
temp.x=array[0];
temp.y=array[1];
temp.z=array[2];
}

note that i used _variable above instead of just "variable", just in case to make sure this isnt used by any normal variable, you can write "blah" aswell, but adding a _ before is recommended.