I have just had a eureka moment.
I have been quizzing a very knowledgeable chap who has made a node.js applet for controlling the dash via WiFi. He pointed me in the direction of a folder but said no idea how it works …
Well I do now…
Folder in question was is /opt/Garw_IC7/channels/
YMMV but if anyone out there is reading about the GARW IC7 dash this is what I have found.
SSID is GARW. You already knew that though right?
ssh
[email protected] password is root
I used WinSCP and ssh connected to dump the files locally from /opt/Garw_IC7/channels/
I then cloned them so I have a none edited copy and a live edit copy.
In the /channels/ folder there are a series of other folders. Ignore them. It seems these are a baseline and all the files you are interested are in this folder
All these files are linked. Its not obvious how.
Open Channel assignments. It will look something like this :

Note the row number. It will help you configure things like the input
You can see here for example that row 10 on the Channel assignments is O2.
Check row 10 on the inputs. Its set to can1_6. I corroborated that with a mk1 eyeball on my dash.
Right , now it starts to get interesting. I think the 8bit values are just a a single can input eg CAN1_6. However, Some of these values are 16bit not 8bit.
If you look at the file input bits this gives us a clue. Check my line 10 out. It says 2, but I think thats 2 * 8 bits

You can of course use your dash to select the second channel or type it in here.
If you follow row 10 , its got the second 8 bit channel in it!
You might want to change the offset. You cant in the dash on the o2. for some reason. Bug? Guess what though - Yep , there is a file for it. I manipulated it in notepad and then reupped the file to the dash. Worked straight away
I now have a fully working Lamba reading on my dash. Delighted with that.
I am now going to reconfig my oil temp to my IAT and find something else to monitor with oil pressure.
I have a physical gauge in at present to monitor the oil temp / pressure so comfortable with these being “fake”
I must admit a GUI version of this would be superb but I can cope with some notepad bashing and SSH.