We have actually imported a number of issues using csv import with the work log's in below format:
Some text;date time;username;time in seconds
Example:
some text;2011-24-10 13:31:24;myuser;300
But it doesnt show the 'Time Tracking' panel for most of the issues and if it does show it won't show a wrong value for Logged
It doesn't seem to calculate the total at all.
Please note it does show the time spent corectly for the work log entries though.