Sorry, we are not clear about your question.
You can create a category using the code you have explained. In regards to creating more then one category, you basically have to execute the code above in a loop. You need to re-start the GroupWise client to refresh the categories collection.
set oList = utilities.stringlist oList.add("Test2") oList.add("Test3") for x = 0 to oList.count -1 GroupWise.Account.CategoryDefinitions.Add(oList.strings(x)) next set oList = nothing