Select All Values In List Box

I have a form with a "results" list box for a sort user defined sort Lets say the values are:

Field 1 (ASC)
Field 2 (ASC)
Field 3 (DESC)

What I want to do is automatically select all these values before submitting the form so I can pass every list box value to the next form whether selected or not. Depending on the number of values in the list box I think I need something like this:

// COUNT OF ROWS FROM ZERO
MYROWS = document.choiceForm.choiceBox.length
MYROWS = MYROWS - 1

for (i = 0; i <= MYROWS; i++)
{
document.choiceForm.choiceBox. ?????????????????????? Code here <<<<

}