That is my main task building query in VST. The idea is:
1. You have a feature class
2. Your feature class have representation
3. Make sure your respresentation rule have been save
in a style file and park in C:\Program Files (x86)\ArcGIS\Desktop10.2\Styles
3. Open VST table
4. Add rule in VST
5. To define the query, what field you want to query and which symbology you want to use
6. To define which symbology you want to use, under tab Preview, search the representation rule in style file you have save at no 3.
Contact me at firstname.lastname@example.org if any.