Zero it just like any other scope... even with the 1 MOA elevation and 1/2 MOA wind the FURTHEST you'll be from an exact dead center zero is .5 MOA on elevation and .25 MOA on wind. Chances are you'll be much closer to an exact zero but the .5 x .25 mis-match is the worst it'll get.
They're great scope for long range and are pretty much fool-proof for elevation adjustments....but the windage adjustment can cause a one (1) revolution out of adjustment error just like any other scope.
For varmints they are good but once your varmint (or other targets) gets far enough out to be smaller than the linear distance of .5 x .25 MOA you may have a little trouble hitting it. I've shot groundhogs right at 500 yards (504 I believe) with a 223 and the M3LR.