Basically the method Noel suggested will flush the TLogs to disk and then shrink the file. Its no difference from issuing a command
backup log <db name> to disk = 'C:\abc.trn'
I'd advise to db a full db backup and then append the TLogs to the backup file that you've created and then shrink the DB Log size. Its much safer this way.
BACKUP LOG <db name> TO DISK = 'C:\MSSQL\BACKUP\<db full backup>.bak' WITH NOINIT , NOUNLOAD , NAME = N'xxx backup', NOSKIP , STATS = 10, NOFORMAT
If you flush the logs away, and had added new records into your DB, there NO WAY you can use any info flushed out from your TLog to recovery anything.
Microsoft Certified Master: SQL Server 2008