You're hard coding the value as 4. Within a script as you've outlined, you'd have to change the value to 5, 6 or 7 to get those values. If you wanted to make these into parameters, you'd need to change your script to being a stored procedure.

For example:

CREATE PROCEDURE MyProc

(@InCo VARCHAR(MAX))

AS

Declare @ReportDateIN [datetime]=GETDATE(),

@OutCo varchar(max) = 8,

@IncludeDetailIN [int]= 1,

@IncludeReleasedIN [int]= 1,

@IncludeHoldingIN [int]= 1

DECLARE @EndDate DATETIME

SET @EndDate = DATEADD(dd, 1, @ReportDateIN)

INSERT CustodyStatusTable

SELECT C.CustomerID AS 'CustomerID',

CASE

WHEN CH.CoID IN (SELECT KeyValue FROM dbo.fnValuesText(@InCo)) THEN 1

WHEN CH.CoID IN (SELECT KeyValue FROM dbo.fnValuesText(@OutCo)) THEN 0

END AS 'InCounty',...

Then you call the procedure and pass the value you want:

EXEC MyProc @Inco = 5;

--or

EXEC MyProc @Inco = 6

That will then execute the proc for 5 or 6, as needed.

Now, questions could be raised about why a VARCHAR(MAX) for a single numeric value, what are you doing with the function, because those look like problematic approaches to data access.