Yes, you can do it. But as explained on stream, you will loose ability to debug source code - debugger will have no information about this virtual "dll file". Of course you will still have ability to debug machine code (assembly).
For example code see this library:
https://github.com/fancycode/MemoryModule It is very small and easy to understand. It basically provides similar functions to "LoadLibrary" and "GetProcAddress" to operate on dll file in memory.
Here's the description how it works:
http://www.joachim-bauch.de/tutorials/loading-a-dll-from-memory/