Hacer zoom y mover mapa SVG

[jtv1972]

var centerLatitude = 19.409612;
var centerLongitude = -99.442749;
var description = 'Golden Gate Bridge';
var startZoom = 4; <------------ZOOM
var map;
function addMarker(latitude, longitude, description) {
var marker = new GMarker(new GLatLng(latitude, longitude));
GEvent.addListener(marker, 'click',
function() {
marker.openInfoWindowHtml(description);
}
);
map.addOverlay(marker);
}
function init() {
if (GBrowserIsCompatible()) {
map = new GMap2(document.getElementById("map"));
map.addControl(new GSmallMapControl());
map.setCenter(new GLatLng(centerLatitude, centerLongitude), startZoom);
}
}
window.onload = init;
window.onunload = GUnload;