vb - read input from text file

I use vb 6.0 to run a sql to which I pass parameters like statrt date and end date from
vb to sql.. and then print results to a file.
Private Function Build_Query(sFileName As String,  customer As String, sFolderLoc As String)



   
    Dim sInput As String
    Dim sOutput As String
   
    Open sFileName For Input As #1

    Line Input #1, sInput   ' Get a line of input from the file(sFileName) and store it in the sInput
                            '  string
   
    sOutput = sInput
   
    Do While Not EOF(1)
       
        Line Input #1, sInput


        sOutput = sOutput & Chr(10) & sInput
    Loop
   
    sOutput = Replace(sOutput, "&BEGDATE", "'" & strBegDate & "'")
    sOutput = Replace(sOutput, "&ENDDATE", "'" & strEndDate & "'")
    sOutput = Replace(sOutput, "&customer_LIST", svcbr)
    Close #1
       
    Build_Query = sOutput
     Open sFolderLoc & "\List_" & Format(strEndDate, "mmm") & "_" & Format(runDate, "mm""-""dd""-""yyyy") & ".txt" For Append As #5
    Print #5, "This Report was run was for  " & customer
    Close #5
   
End Function


and then I make a call to the function build_query like this:
customer = "(1,7)"
    sSQL = Build_Query(SQL_Home & "\sqlFileName.sql", customer, sFolderLoc)

If you notice I am hard coding the cutomer list like this:customer = "(1,7)"
Instead , I want to create a text file(using notepad) and store the customer values there in a folder and then use
that in my code,, so that every time the user changes the customer list, I dont have to change my code, instead i can just
change the text file contents.
How do I do this? Please add changes to my code to be specific.