You can make a live backup of the transaction log using the dbbackup utility with the-l option.
Making a live backup of a transaction log
Set up a secondary machine from which you can run the database if the online machine fails. (Install and configure Sybase IQ on the secondary machine.)
Periodically, make a full backup to the secondary machine.
Run a live backup of the transaction log to the secondary machine.
dbbackup -l path\filename.log -c "connection_string"
You should normally run the dbbackup utility from the secondary machine. If the primary machine becomes unusable, you can restart your database using the secondary machine. The database file and the transaction log hold the information needed to restart.