If you right click in the graphics area (FrameBox) and select Customize, a winodw will appear. Press the plus sign and this will add a script window. It seems graph builder counts from zero. Figure 1 shows this script window. Attached is the saves script for this graph.
Add more YFunctions() using the same cutpoints. In other words, there will be two YFunctions() for each category. As stated above the categorical axis in graph builder is 0 to #categories -1 and the cuts are halfway between. I *think* in the Variability graph, counting is from 1 to #categories, where the # of categories depends upon the number of subgroups.
If you have fixed limits all is okay. However, if you are scripting and reading the specs as variables, and you journal the graphs to be opened later, investigate the message Freeze. When using variables in a graphics script, the variable names are stored but the values will not be in memory, when you reopen it. Freeze stores the picture as is. Otherwise, you need to do a little extra to get the values not the variables in the script. If you specify, where these limits come from, or whether you will be scripting this graph or creating it interactively, then some one on the blog will provide you an example.