Have a look at the following:

IB LogManager
The Logging Tool for Interbase/Firebird Logs every data changes in an
Interbase/Firebird database in a user-friendly way.

1 User License $45.00
2 User License $89.00
5 User License $169.00
Site License $259.00

30 Day Evaluation Download IB LogManager exists as stand-alone application,
IB Expert PlugIn or as EMS QuickDesk PlugIn, therefore a number of different
evaluation downloads are available.

OK its not free, but its not that expensive either, and it may be the
solution you are looking for.
You can follow the link from

http://ww.ibphoenix.com/ibp_contrib_download.html
Look under miscellaneous tools.

Regards
Paul Beach
Main Tel (UK):+44 (0) 1844 354465
Mobile: (UK): +44 (0) 7764 188603
http://www.ibphoenix.com