SQL stored procedure with list

I am trying to create an SQL stored procedure for a .net programmer that may
pass a list in one parameter.
It works if I only pass in 1 item part number. The .net programmer said he
had it working in sequel server and he could pass item1,item2,etc.
Here is what he gave me from the sequel server:

CREATE PROCEDURE some_name

@productNumberString VARCHAR(750)='''000000'''

AS

DECLARE @select VARCHAR(150)

DECLARE @where VARCHAR(800)

SET @select = 'SELECT
imdsc,impn,pscmrn,imlots,psqtyn,cost1,cost2,cost3,cost4,cost5,cost6,cost7
FROM PNOTEBOOK.NBKSUM WHERE impn NOT IN '

SET @where = '(' + @productNumberString + ')'

EXEC(@select+@where)

GO

This is what I created. I can't figure out how to pass this as one string
for a DB2 stored proc.

CREATE PROCEDURE GetItemNot
(in NotInclude varchar(800))
RESULT SETS 1
LANGUAGE SQL
BEGIN
DECLARE c1 CURSOR FOR SELECT
imdsc,impn,pscmrn,imlots,psqtyn,cost1,cost2,cost3,cost4,cost5,cost6,
cost7
FROM PNOTEBOOK/NBKSUM
WHERE impn NOT IN (NotInclude);
OPEN c1;
SET RESULT SETS CURSOR c1;
END

Thank you,

Craig