Custom Client side validation using IClientValidatable. ASP .NET MVC 4

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ASP

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MVC

Hello All,
I am trying implement custom client side validation.It is a cross coupled validation. I have followed all steps and its working fine. But my requirement requires me to modify the ErrorMessage which is will be part of metadata(HTML 5 Data Attribute). The example is as follows
IClientValidatable implementation:

public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
       {
           ModelClientValidationRule rule = new ModelClientValidationRule();
           rule.ValidationType = "salaryandloanconstraint";
           rule.ValidationParameters.Add("loanconstraintvalue", _loanEligibleMultiplicity);
           rule.ErrorMessage = "Salary Insufficient to sanction a loan amount of";
           return new ModelClientValidationRule[] { rule };
       }

The message which i have initilized to rule.ErrorMessage is incomplete. I want to append text which is taken from input feild for LoanAmount property to the error message when the user enters.

In Summary is there any way which i can manipulate the error message(HTML5 DATA ATTRIBUTES) at the client side using JQuery?