Here is the syntax:
rmi.navigate('linktype_rmi_slreq',RequirementSetName,RequirementID)
For example, if I have a requirement set named 'CruiseControl', and I know the ID of the requirement of interest is 29, I would use this command:
rmi.navigate('linktype_rmi_slreq','CruiseControl.slreqx','29')
The ID can be found in the ID column in the Requirements Editor. You can also use other functions in the Requirements Toolbox APIs to get additional requirement object attributes, such as slreq.Requirement. The requirement ID is the "SID" property for a Requirement object.