Unfortunately there is no such feature currently in 406 to link module type with individual work item in RTC.
The concept of using link type for Module is explained in the Help:
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Typically, groups of requirements are organized in collections or modules for review, approval, and management purposes. For example, the high-level requirements that constitute the project vision are often grouped in a single collection or module. The requirements analyst, project manager, or development manager links the collection or module to a development plan in the CCM application. The development manager can generate plan items from the each of the requirements in this collection or module. The test manager links the same collection or module to the test plan for the project. The test manager can generate high-level test cases from the each of the requirements in this collection or module.
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Basically module is a group of requirement artifacts and it is corresponding to Plan item in RTC and Test Plan in RQM
and won't go to individual work item or test case. You can only link individual work item or test case for each requirements within the module. Creating a new link type won't help here.
If you have a strong use case, you may want to submit a request for enhancement(RFE) from here:

https://www.ibm.com/developerworks/rfe/execute?use_case=changeRequestLanding

(you will need an IBM ID(free registration) to submit a RFE)