Street view is not a feature that is available in Pro maps, though you can modify the promaps .js file to include it.
First you need to add a div to display the street view panorama:
<div id="pano" style="width: 300px; height: 300px;"></div>
next you need to modify the maps .js file to add street view.
in the .js file, find the following line:
var map = new GMap2(document.getElementById('wagmp_map_1'));
the number "wagmp_map_1" may be differant.
and add the following after it:
var myPano = new GStreetviewPanorama(document.getElementById("pano"));
Then find each occurance of:
map.addOverlay(marker_0);
the number in "marker_0" my be different and will change depending on how many addresses are in your map.
and add the following after it:
svOverlay = new GStreetviewOverlay();
map.addOverlay(svOverlay);
myPano.setLocationAndPOV(point);
GEvent.addListener(map,"click", function(overlay,latlng) {
myPano.setLocationAndPOV(latlng);
});