The short answer to your question is that you will have to write code to do this. You could theoretically use two UltraValidators, one for a date range of two months ago through the current date, and another for the current date and later (the form'er error message would be a "warning" and the latter's an error), but I don't ever recommend using two validators on the same control.

The following code sample demonstrates how to use the ValidationError event to change the error message that is displayed to the end user based on how "far" the validated value is from some arbitrarily defined value, in your case, 2 months before the current date:

this.ultraDateTimeEditor1.NullText = "00/00/0000";
this.ultraDateTimeEditor1.Value = null;
ValidationSettings vs = this.validator.GetValidationSettings(this.ultraDateTimeEditor1);
vs.ValidationPropertyName = "Value";
DateTime maxDOB = DateTime.Today.AddMonths( -2 );
vs.Condition = new DOBCondition( maxDOB );

public class DOBCondition : RangeCondition
{
    public DOBCondition( DateTime maxDOB ) : base(DateTime.MinValue, maxDOB, typeof(DateTime) ){}

    public enum WarningType
    {
        None,
        Warning,
        Error
    }

    public WarningType GetWarningType( DateTime value )
    {
        DateTime maxDOB = (DateTime)this.MaximumValue;
        if ( value > DateTime.Today )
            return WarningType.Error;
        else
        if ( value > maxDOB )
            return WarningType.Warning;
        else
            return WarningType.None;
    }
}

private void validator_ValidationError(object sender, Infragistics.Win.Misc.ValidationErrorEventArgs e)
{
    ValidationResult result = e.Validation.Errors[0];
    ValidationSettings vs = e.Validation.Errors[0].ValidationSettings;
    UltraDateTimeEditor dateTimeEditor = e.Control as UltraDateTimeEditor;
    if ( dateTimeEditor != null && vs.Condition is DOBCondition )
    {
        DOBCondition condition = vs.Condition as DOBCondition;
        DOBCondition.WarningType warning = condition.GetWarningType( (DateTime)result.Value );

        e.NotificationSettings.Caption = warning.ToString();

        switch ( warning )
        {
            case DOBCondition.WarningType.Warning:
                e.NotificationSettings.Text = "Warning : xxxxx!!";
                break;

            case DOBCondition.WarningType.Error:
                e.NotificationSettings.Text = "The date of birth must be before today";
                break;
        }
    }
}