Requirement traceability matrix with Redmine (brainstorming)

Q:
1. How to write a requirement traceability matrix with Redmine?
-> It is hard
2. Is there any Redmine plugin available to simplize this?
-> http://www.redmine.org/plugins/redmine_traceability
3. If no plugin is available, is there any way to customize, make use of
Redmine to do that?
-> "redmine_traceability" is good but it does not fulfill the
requirement that PMBOK shows.

My approaches:(No plugin is required)
- Define list of (IDs of) test cases,
- Define list of (IDs of) functions, modules, requirements,
- Preferly, each of them in a separated issues, tracker or a project,
- Link requirement ID with corresponding issues (test cases, functions,
modules).

Drawback: Hard to track, this will not easy to see in form of a "matrix".
Cons: Easy to implement, not special requirements needed.

Cf. http://en.wikipedia.org/wiki/Traceability_matrix
Cf. http://www.redmine.org/plugins/redmine_traceability