Adding Custom Columns when Creating A Dataset via the API

Is there a way to create a calculated column when creating a dataset.  

Folliwing the API reference: https://msdn.microsoft.com/en-us/library/mt742155.aspx

It seems we can create an Expression for a Measure, but maybe not for a Column?  I would like to add an If Statement on a Measure as a Custom Column.   This is easily accomplished in Desktop, but not sure if the API supports this or not.