If you go over to Swarovski's web site Here
you will find a TDS calculator. Enter your information and you will be all set (or pretty close). You will need a valid serial number.
I believe you can make a chart for whatever power you want.
Your zero will stay the same for every power setting. You'll have to make the proper chart for the power setting you want. You should be able to make multiple charts without re zeroing. I suggest verification of those charts though.