Hello, sparky.
To start your script with the push of a button, you can add some code at the beginning of your BEGIN/REPEAT loop that stays in a while loop until a button is pushed. For example, you have your button connected as an input on channel 5, you can add this while loop to have the script wait for the button before continuing:
begin
5 get_position 500 greater_than while #wait in while loop until button connected to channel 5 is pushed
repeat
If you try adding something like this to your script and have problems, you can post the script you have so far and I would be happy to help troubleshoot.
Brandon