If you can download the map tiles to your offline storage, you can use a custom provider to read the tiles from your computer.
string MakeTileImageUrl(GPoint pos, int zoom, string language) {
long x = pos.X;
int num = 1 << (zoom & 31);
long y = (long)num - pos.Y - (long)1;
string str = string.Format(LocalFileProvider.UrlFormat, zoom, x, y);
if (System.IO.File.Exists(str)) {
return str;
}
return "maptilesofflinefolder/empty.png";
}
static readonly string UrlFormat = "/maptilesofflinefolder/{0}/{1}/{2}.jpg";