Parameter input dropdown in Crystal XI

I am using Crystal XI and using the dynamic list of values from a stored procedure for the parameter field . So I get this interface with a dropdown where all the values are populated and the user can choose the value and run the report.
But it doesnt let the user input any values on his own , basically it is a readonly dropdown . Is there anyway I can have the option for the user to input values as well as using values in the dropdown? I am not creating an asp/aspx page here . I only use the crystal report XI to develop this. Thats where I have to figure out a way to make the dropdown take user inputs as well.

thx