My friend had an old Navman S30 he wanted to install Igo on. It was actually a quite simple process.
First back up the contents of the flash disk to your computer in case anything goes wrong.
Find the folder called Program files in the flash disk.
Inside this is a folder called Navman which in turn contains another folder called SmartST_CE and an application called AppStartupSec.exe
Delete the contents of SmartST_CE and replace them with the contents of the Igo folder ie content. licence, data zip etc ( In my case I used Igo 18.104.22.168297) ie the Igo folder is now called SmartST_CE. (or you could simply rename the Igo folder to SmartST_CE)
Rename Igo.exe to SmartST_CE.exe
Delete all the rest of the Navman crap to free up space (You might want to do this first)
You should now have the following structure on the flash disk.
Program files / Navman / SmartST_CE (plus AppStartupSec.exe) / (Igo files)
The device will now boot straight into Igo after the initial splash screen.
To make backlight work properly, I have been messing around in system text and have put in the following under power.
backlight_manage_values = 1
backlight_manage_keys = 1
backlight_max = 100
backlight_min = 0
backlight_reverse = 0
backlight_methods = 39
backlight_events = 1
Very effective and it has given me sliders for both the daytime and night levels.
Volume on the other hand is excellent.
Should work with any version of Igo, Amigo, or Primo