It's a bit tricky so you better be careful when attempting this.
I used a hex editor to figure out which real definition OFT is using for my ECU. Downloaded the original Romraider def from
https://github.com/TD-D/SubaruDefs/t.../RomRaider/ecu
Edited the definition to add values for some of the missing tables.
If you're not sure what you're doing you can brick your ECU by mistake . If you check the tips and tweeks threads on the forums you'll know which tables are missing (at least the ones you might be interested in changing/tweaking).
Sorry for the late reply. Was on a holiday leave.