So there are two options i know of. fw log $LOGFILE | gzip -c > /some/path.txt.gz
This will be .. very slow.. if you want something more useful look up the following switches to disable ip object looking up and service object look up. Double check those switches. Been a while since i've done this.
-n -p
You will only get raw IPs in the logs but it will export 10 times faster. Maybe that is not true but it will be very much faster. Then you can index the raw text files however you see fit. For extra points, dump the obejcts database as a xml file. Then you can create a dictionary to map IPs to checkpoint hosts objects / gateways if you wish.
If you only want allowed traffic then i think you can add -c accept (or something like that).
fw log --help
should show all options.
There is one other option to always print the full time stamp that might be useful.