SETUP
1) Create a Map Document (mxd) with at least one elevation layer; the elevation layer must be a single band raster layer. Other types of layers are ok to use because the SOE will only expose a resource for the single band raster layers.
2) Publish the Map Document as a Map Service and then stop the map service after it has been successfully published.
3) Right-click on the map service and select �??Service Properties�??. In the �??Map Service Properties�?? dialog, select the �??Capabilities�?? tab.
4) From the list of capabilities, check on the new �??Get Elevations�?? capability and click the OK button.
5) Start the map service.
6) Go to the Services Directory admin page and clear the REST cache.
7) Navigate to the Services Directory page of the Map Service and you�??ll now see the Elevations SOE listed at the bottom of the page in the �??SUPPORTED EXTENSIONS�?? section. Follow the available links to view the available REST resources and operations for the Elevations SOE.
news: esri is coming out with the new version x 10.1 and the included source net and java
here you can see my preview beta http://sit.sistemigis.it/Samples/Elevations/
however you download esri version ...