Unfortunately it will be mostly up to experimentation with regards to where the BDC chevrons land for 5.45, as well as how many clicks you can adjust the turrets to get the primary chevron on target at longer ranges.
The nice thing about the POSP is that once you have it zeroed at you preferred range, you can reset the indicators on the turrets. This means once you get things dialed in, you can make notes of it and make it easy to recall which values you need to adjust to to be on target at any given range.
I have read that the 5.45x39 and 7.62x54r trajectory end up being very close and therefore the 1000m rangefinding version may be the closest to "correct" for 5.45 but I have no idea if this is really true.
Edited by mancat, 02 April 2015 - 12:13 PM.