I used the TENS largely in desperation due to all the disabling symptoms. Many of those would probably have been diagnosed as dysautonomia had I been able to get proper medical care.
The electrodes went on the stragus of one ear and lobe of the other.
I used it over 3-4 days and the continous breathlessness went away, almost completely.

I also used a different array (placement of electrodes) on my ankle for urinary incontinence. That also worked, but only if I used it every day. Because I wanted professional guidance that was not available to me, and other LC patients were reporting problems with exacerbated symptoms in their self-treatment with TENS. I stopped.
Finally a visit to a neurologist, who didn't really understand what was going on with LC, got PT referrals, but I couldn't really drive, so never got that expert guidance.
I know TENS can help with pain and did help me with 2 of the most limiting LC symptoms at that time.

I hope that helped. I tried to upload a less personal and more comprehensive description of TENS yesterday but it was too large.