I strongly suspect that our own ghostie here must know quite a bit about the BDCs of Kahles ZF-69 scopes.
Well, I don't know tons, but I do know a few things. Some of this may be obvious, or already well known to you, but...
There is a manual for the SSG69 which is several places online. It can be found here.
http://www.steyrarms.com/fileadmin/user/pdf/SSG_69_PI_PII_PIIK_PIV.pdf
I think there are some other manuals as well. In the above one, it goes through the sight-in procedure with the ZFM, which is a very similar scope to your ZF69. One of the weird things about the manual though, is that it talks about "clicks" being .1 mil. The ZFM I have (and I believe the rest of them) do not have "clicks" in the sense of an audible click like most modern scopes. What they have is "hash marks" on a dial. The turrets themselves have a relatively stiff continuous range of motion. The hash marks on the windage dial, I suspect those are 1 Mil. But between them you can sort of "eyeball" what you want. Divide the little space into 10 in your mind and make "smidge adjustments according". This actually works really, really well, once you get used to it. Same with the elevation.
On the elevation dial, there are some hash marks that have a letter associated with them "1", "2", "3", etc., and some in between them that don't. I believe it goes up to about 12. What I would probably do is sight it in a 100m (not yards), just by turning the elevation dial to what it needs to be to hit the target dead centre at 100m. Then loosen the three screws, pull the dial up and gently bring the "1" hash mark down right on top of the arrow - and then tighten up the screws. Confirm that you have got it spot on-at 100m. Then, if you can, put it on "2" and shoot at a known 200m target. If you are on the money at 200m, then it will probably work all the way up the scale out to 1200m.
There are a couple of different dials for these scopes. I know there is one that is about right with 168gr. Federal Gold Medal Match (or similar), and another one that is pretty much on for 150gr. American Eagle (or similar). Hot handloads will probably shoot high. If you are shooting 168gr. to 175gr. bullets, I would probably try and duplicate the performance of a Gold Medal match round as a starting point, and then figure it out from there. If you are hitting low at 200m, you may have to increase the speed (powder) a bit, re-zero on 100m and then adjust from there.
Conversely, you could zero at 200m and adjust your load from there. Keep in mind, with these 6x scopes you pretty much need a spotting scope at 200m to really be able to sight in properly.
This is all for the ZF69, ZFM, ZF85, ZF95-type 6x42 scope with a "German" three post reticule. There are some 10x models that have other stuff on the reticule, but these are less common.