This should only take some minor critical thinking
With the zero stop loose, zero your rifle at what ever distance you choose.
Take your turret cap off and align the 0 mark with the line and push cap back on.
Dial down your 1mil
Remove cap and set zero stop
replace cap in the same orientaion (I think 9 should be aligned with the mark. I'm not very familiar with mils)
Dial back up to zero.
Double check zero at your distance.
Done