Sometimes this is a programmers first experience with using Bitboards and MCTS. To this end I created a small example of how to implement Bitboards for plain TicTacToe. Instead of MCTS, this example has just Monte Carlo (also called MC, FlatMC or 1ply MC) origional and updated with feedback from darkhorse64
The example shows how to effectively use bitboarding to get 500,000 simulations within 99 milliseconds, and how something as simple as plain Monte Carlo can achieve good informed results. I know of 3 CGers LazyMammal, BugKiller_328, and KP56 who used Bitboarding and plain MC to achieve Gold, Gold, and Silver respectively.
Plain MC is very straight forward to implement. You effectively just play random games and track which starting position resulted in the most wins. It can also be entirely reused to make MCTS when you are ready.