Import GIT repository into RTC source control

I suggest identifying the "important" baselines from your GIT repository.  Once you have these identified, create a development workspace in Eclipse, and pull down the OLDEST baseline from your Git repository into this workspace.  At this point you can put this code under source control in Jazz, and create the component(s) that make sense.  Now create an initial baseline in jazz.  Now pull the second oldest baseline from your Git repository into the Eclipse workspace.  At this point RTC will identify all of the changed files, and you can check in your changes under a single workitem and changset.  Now create a new baseline for you component(s) in Jazz.  Keep repeating this sequence of "copy from Git, check into Jazz" for all of your important baselines in Git.  You will end up with a series of baselines in your Jazz components, and you will be able to go back and recreate a workspace from any one of these baselines and potentially create a new stream based on that baseline).

So you end up losing the user information and time/date information from the file changes (since they all show up having your name and the date/time of import into Jazz).  However, you do have a history of the changes made to the code base over time.  You also get the ability to go back and see which baselines were associated with particular changes.  It's simple, and it's brute force, but it works.  Hope this helps.