When you first bring up the scheduler, up you might have to tab around but you should find a check box to enable the scheduler.
If you have the scheduler enabled and you tab, you should find the first of two radio buttons, the one for at specific times.
You should be able to up and down arrow between the two radio buttons.
The second radio button is for at regular intervals.
If you are on radio button one, you should be able to tab and find a set of three checkboxes each when checked provide an edit field to enter a specific time.
Or if you pick the second radio button for regular intervals, you should be able to tab to a combo box and pick a selection.
So up and down arrow to choose a radio button, then tab. The other thing the scripts do is allow you to regain focus in the juice window after minimizing the program. If you bring up juice and you don't have focus, press control shift L. This should place your focus in the listview and allow you to arrow up and down.