"Obtaining gain metrics from a decision tree model"

Hi --

Once I've run a DecisionTree learner, is there a way to obtain the attribute selection metric that was computed at each node (e.g. information gain or gain ratio)? 

I'm using ModelWriter to output the results, but I don't see that information there.

Also, is there an option to obtain other information such as fraction of data that was split at each node?

Any help much appreciated.

Thanks!