If you do not want to analyze a live log file on a production server, there is a bit of a procedure that you need to follow. First of all, you need a collection of backup files: The last full backup and all of the log backups up to the current time.
First, restore only the full backup to the offline server so that the database is operational. Next, start Log Rescue and point it at the database. Next, add all of the backup files (starting at the latest FULL that you had just restored and then all of the log files afterwards).
Start the analysis. Log Rescue will now show you all of the transactions contained inside the transaction log backups (rather than the live log).