this is what i do to skip "Your contry not suported" screen,
(my device is rooted).
1.instal viago.
2.instal "fake gps" apps from playstore.
3. disable network/wifi location, also disable GPS.
4. run fake gps, set to US, or europe.
5. run Viago, confirm some dialog from viago, wait until "ready to navigate" appears.
6. then you can close viago, and instal any IMG map.
dont wory, after you sucess with skip the "country not suported" page, it wont ask you anymore, so now we can remove fake gps apps, and use our "real" GPS.
so basicaly we only use "fake gps" apps to virtualy detect our location as suported region (US/europe) only on initial page when running Viago for first time.
i hope this help. tested on my chinese ICS device, with indonesian map (.img).
problem: i still cannot make route to works, so i guess route didnt work on unsuported country.?