When you say 'parameter pop-up', do you mean you have a variable in your query, that isn't specified within the query itself...
So something like:
Code:
SELECT something
FROM something
WHERE state = inputState
Then the popup asks you to input 'inputState'?
If so, then as far as I know, you can't alter that popup to contain a dropdown box (at least not easily, and therefore not worth pursuing). You could alter the way in which the report(?) is generated, by adding a button on your form to generate the report, taking into consideration the value currently displayed in the state dropdown box.
Is that what you're after?