I have a problem with conditionalStyle in iReport. I have the following textFields (${nameField} = field value):
${field1}=30  
I could not find a direct way to accomplish this task - you have to create a separate style for each field.
Considering this you can concentrate your effort on creating a small script that replicate the XML with the same stile for the fields you have. Then you can just copy/paste the XML into the report source file. Each time you need to change the style you will have to go back to your XML generator.