I'm amazed that you are asking this question *after* you have had a disaster. This is the sort of thing you should have implemented and tested as part of deploying your system. Anyway, the answer is straightforward.
On the failed machine, re-install TimesTen and configure it exactly the same as it was configured prior to the HDD failure (including the DSN in sys.odbc.ini). The run the ttRepAdmin -duplicate command, with the right parameters and options (be sure to use -setMasterRepStart for example) on the recovered machine and once this has completed start the rep agent for the database on that machine. After a while the databases will be in sync again. In order to minimise the time needed for re-sync you should issue a checkpoint command on the primary database before starting the duplicate operation.