There are a couple of options here. The first, you can use dlls to dynamically load your next move finding function. With the correct setup, the find move function would be in a dll, and the user can select which dll's function to use. Ill refer you to the MSDN for more information.

The second option is scripting, writing your find next move function in some sort of scripting language. There are several canned ones on the net (Lua, Python, Javascript, etc), or you could write your own. Google would be your best bet, this time.

Z.