Dashboard indicator lights

[nstn8]

I just have a few questions about the indicators on the dashboard, probably because I don't have the service manuals. I was wondering if the instantaneous mpg was a signal going to the dashboard that could be tapped into, or is it calculated in the dash? Also I have a MT I was wondering if the shift up and shift down lights can be disconnected and used for something else easily or if this was not a possibility.

Thanks in advance,
Nate