MoS2 is a black, solid, inorganic material. It is not in the least bit oil soluble but it can be dispersed as very fine particles in oil.
MoS2 is roughly 60% (by weight) Molybdenum and 40% Sulphur. 50 mls of 100% PURE MoS2 in 1000 mls of oil would put about 3% (or 30,000 ppm) of Moly into the oil. However the commercial liquid stuff you add to oil is almost certainly MoS2 already suspended in oil. I don't know what concentration they use but if the commercial stuff was 10% MoS2 in oil, then 50 mls is 1000 mls would put 0.3% (or 3,000 ppm) of Moly into the oil.
Not sure if Liqui-Moly contains Boron but I've always thought of Boron's presence in lubricants as being somewhat over-rated.
Be aware that MoS2 in an engine oils acts solely as a solid, plate-shearable lubricant (like graphite does in your vacuum cleaner). It's not an antioxidant and probably not a friction modifier either.
If you want to read a nice little presentation about MoS2, I found this on Google. As someone that's never used MoS2, I found it rather educational (although I still personally wouldn't touch it with a barge pole!).
http://schaefferoil.de/sheets/praesentationen/factmoly_en.pdf
PS - Thinking about it, one of the things that might bother me about MoS2 use is its impact on sulphated ash. MoS2 does seem to be pretty thermally stable so does 0.5% MoS2 in oil add an extra 0.5% to the ash level? If so this would be significant and although I don't do all girly and weak at the knees about ash levels in oils, too much might give rise to spark plug fouling that that I would be worried about...