I have the freediag code, but haven't had time to get it going yet. The interface that it uses is available from: http://www.andywhittaker.com/
Another good interface is: http://www.multiplex-engineering.com/
I started writing the code for the empeg, and got as far as writing the screen routines to output the various available engine params, as text and bar graphs.
I have just received a new 60Gb empeg, which is going to stay in the house (and on the LAN) so I may get a chance to carry on with the project.

Philb.