Man, I don't know if it's a mistake in the file you created or that you tried compiling them like that, but you were missing A LOT of files there.
And you had one code problem there (#include "BetterBTSAI.cpp" instead of the .h file).
I attached the full folder of files - all sources, project file etc. - so you can compile it yourself (just set the makefile folders correctly).
As a bonus I also added the debug dll itself in the Debug folder.
Note that if you build it again, this file will be overridden.
BTW, sorry for not being responsive. I hadn't been to CFC in a long while.
(All of this is just in case you still need it)