I just got the iNav software yesterday, and used the DeLorme software to make my Earthmate receiver work with it.
Same as you, I tried the various settings, to no effect. Then, suddenly, everything just worked.
I don't know what I had been doing wrong; it could be a simple as starting one program before the other. All I know is that it eventually works, and seems to work well. I'd suggest you buy the software--I like it very much, even more in some ways than my wife's new TomTom.