No need to truncate the log and break the log chain to fix fragmentation. Pick a time the DB is not heavily used (not used at all is better) and the active log is at the beginning of the file. Take a log backup, shrink the log to 0, grow it back to the desired size in however many chunks you calculate for the VLFs you want.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability