Short and long term fuel trims don't seem to be available on the EMS2000, but maybe they show up in EOBD mode.
This might be one of those things that I could add so that you can see them in Rover EMS2000 mode as well.
See if you can get short and long term fuel trims to display in EOBD mode.
If it does then it should be possible to log it to a file as well.