Add Argument to IndexOptimize.sql to Execute Custom Command After Each Index Is Processed

I need some way to check the space usage and backup the transaction log of the database before it gets full when we run your IndexOptimize.sql script. Our databases are mirrored, so I cannot change their recovery model. Btw, our log files grow hundreds of Gigabytes. One possibility could be to execute custom commands after each index is processed. This custom command would be designed by the sysadmin to do any custom action, in this case to check the logical space used by the transaction log file and to do a backup log if it is greater of a percentage. Can you add an argument into your script to do this? Is there any other way to avoid this problem?