As I understand you want to get all error messages on a specific form and style them further. For that purpose you can first get them using jQuery selector by class and add your own css class:
Please let me know if I understood your question or whether you need further help.
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items