I think you are looking for the AddCurrentRange method. It takes 3 parameters: LowVal, HighVal, Include. The include value is numeric and specifies if the low and/or high values should be included. The possible values are in the Developer's Help file.
>I have a report with a report with a parameter field that is a range of numbers.
>I have used the following code for a discrete value parameter field.
>How do I pass the high and low range values.
>
>CRApplication = createobject("CrystalRuntime.Application")
>CRReport = createobject("CrystalRuntime.Report")
>CRReport = CRApplication.openreport(&thisreport)
>ocparm=CRReport.ParameterFields()
>oparm=ocparm.Item(1)
>oparm.SetCurrentValue(begsqlkey)