1. 
ImageList ImageList1 {
    IconWidth = 32;
    IconHeight = 32;
    /* LargeImageプロパティで$TRUEを指定する*/
    LargeImage = $TRUE;
    LoadIcon("html");
}

2. 
ImageList ImageList2 {
    IconWidth=32;
    IconHeight=32;
    /* LoadIconの引数で1を指定する*/
    LoadIcon("html",1);
}