Training my neural network to overfit my training dataset
If you want to overfit, then yes you just need to keep fitting the training data through your network until you reach as close to zero training loss as possible (note that zero loss is stronger than 100% prediction, and will result in a greater amount of overfitting). There is no need to use cross validation. If your network is sufficiently complex, then it won't take very long to reach very high accuracy on the training data.