For those interested, I found the answer I was looking for from Warp, over at FS Developer. Posted the same question there. Warp WROTE the gauges for the Eaglesoft Hawker 400 XP. The issue is ISG1 gauges will not talk to stock aircraft gauges because of the coding within the ISG1 gauges. No idea why ISG1 would write them this way but it seems to be true. Now, what is also true is that they will not update say PFDs on some or many other 3rd party gauges for the same reason.
Now the reason I only wish to use ISG1 Smiths FMS is because this particular aircraft did not come with an FMS as it is a FS9 bird.
My work around?
I am using the original aircraft PFD within another window. I simply copied the Hawker PFD to the same window the Garmin 530 occupied as I can update the Hawker PFD via the Garmin, and then my main panel EADI with the FMS and fly as per documentation. Unless I missed it, I know of no other way to update the FSX flightplan via ISG1 Gauges. Does anyone know of a way, did I miss something? In the end it is worth it to have some kind of FMS on board. I actually fly the Hawker 400XP for a living and this is the best I have found anyhow to date. I like to use FSX to prepare for checkrides as FAA checkrides have about as much to do with day to day flying as... Not much. LOL.
At some point it would be nice if someone can give some information as to why ISG1 is such a closed product, too bad it can't do more, OR have more variety of PFD/ EADIs to work with, IE Proline 21 or Garmin 1000/3000 that many current Biz Jets are going to. Well for those of us who like to fly Biz Jets instead of Tube Liners.
Again, if anyone has any other ideas, info, opinions, let's hear them. Maybe I overlooked something which is all too possible. THANKS!!