The lavadrive is a boost driver, which means all you need to worry about is setting a current. It will take input voltages from 2.5-5.5 Volts. If you are going to use 6 volts, solder the included silicone diode to the driver (read thread for more details). For the Rckstr driver, you will need to input above 5 volts, because it is a linear driver. Don't get me wrong, his drivers are great!
If you don't have a Digital Multi Meter, you might wanna ask drlava/rckstr to preset a current on the flexdrive/rckstr driver for you. For a StoneTek diode, the current needs to be from 280mA-350mA, but I would say that 350mA is pushing it a little. 300mA is the sweet spot for these 16x diodes. For a 20x Open can, 420mA is the sweet spot.