Sql – SSRS 2005 – Capturing RAISERROR message

I am checking whether a user has a permission to view the report through dataset stored procedure and if the user doesn't, raiserror is called.

Is there a way to display a different message from SQL Server Reports 2005 when a stored procedure (that populates report dataset) raises error (through RAISERROR) instead of returning data?

Here is a skeleton code of dataset stored procedure

create procedure ReportSprocName
    @ClientID   int,
    @Login      sysname
as
begin
    --; check user's permission through @Login
    --; * Pseudo code *
    if @Login does not have permission begin
        raiserror(@Login does not have permission, 127, 1)
        return
    end

    select  id, name, etc...
    from    someTable   
end
GO

I am interested in two possibly solutions

1. Displaying error message within RAISERROR
2. Displaying a hardcoded custom message in SSRS report itself

Currently this is the default message displayed by SSRS reports