Hi! Well, after searching a lot, I realized that what UDK does is... complicated in a custom engine. I think you got 2 ways to accomplish something similar:
1. You can use the Remote Connection that Wwise Studio provides. It works fine. It got two problems though: depending on the machine you got and your engine performance, it can go very slow and drop fps to the ground. The other problem is the axis reference. I use Right Handed in my engine (Y is up, X i right and Z point from the screen to your face). And wwise uses a different one. I know there's an option in FMOD to change that, but I didn't find It on wwise.
2. The other option is you render it. You can get, for each Wwise Game Object, the properties. So maybe you can use them to render it within the game. I didn't implement that because I haven't enough time, but could be a nice option.
Good Luck, let me know If you find something