I figured it out. So far so good.
Some VSTs, some free ones ( .dll ) seem to work great. Just copy and paste into your VST folder.
Some free VSTs also cause some errors. But few and rare.
To install some paid VSTs like Minimoog, Native and others, make sure you install them, meaning run the installer for the VSTs and install into same Bottle as FL Studio.
In other words, Install FL Studio 10 into a bottle name like "FLStudio10"
Then,
Install the other VSTs that have installers, into the same bottle "FLStudio10"
Works perfect and seamless now! Well, when closing down FL, it usually asks if I want to save the file if I tweaked it. I just closes without asking for a save. So remember to make saves yourself.
No need for Bootcamp, no need for Windows OS!
Works Natively in Mac OS with crossover ! Great product !
15" Macbook Pro 2011 - 2,2 GHZ, i7, 500GB 7200RPM, 4GB RAM, High Res Display.