The Box command only takes in raw data, but you can construct a box and whisker diagram by combining commands.
We uploaded an example file (File\On-line examples) that will do this for you.
The format of the data looks like this:
You would also need to calculate the left and right location for each box. We set this up using a slider variable, so you can adjust the width quickly.
Then three commands are set up that combine to create the box and whisker.
You can download the example file and paste in your data.
Is this what you wanted to do?