The flexmod has two potentiometers on it, one for setting the idle current and the second for setting the modulation current. You'll need a 5v power supply along with a source to run the actual driver. 9v batteries have very low capacity and I'd recommend against using them as the voltage can drop extremely rapidly, leading to a setting on the driver that could blow up your laser when you connect it to a normal power supply.
With the modulation input grounded, set the idle pot to just below the lasing threshold - then apply 5v to the modulation lead and set your full running current.
The correction amp needs to be tuned to provide +/- 5v on the X/Y channels and 0-5v on the modulation channels. The best way to do this is with an oscilloscope, but it can be done other ways.